diff --git a/internal/database/counts_internal_test.go b/internal/database/counts_internal_test.go
index 76f52be..3fcd7b5 100644
--- a/internal/database/counts_internal_test.go
+++ b/internal/database/counts_internal_test.go
@@ -148,7 +148,9 @@ func TestLiveCountsTrackWritesInRealtime(t *testing.T) {
 func writeASNsPrefixesAndPeers(t *testing.T, db *Database, ts time.Time) {
 	t.Helper()
 
-	err := db.GetOrCreateASNBatch(map[int]time.Time{64500: ts, 64501: ts})
+	seen := SeenTimes{First: ts, Last: ts}
+
+	err := db.GetOrCreateASNBatch(map[int]SeenTimes{64500: seen, 64501: seen})
 	if err != nil {
 		t.Fatalf("GetOrCreateASNBatch: %v", err)
 	}
@@ -164,14 +166,14 @@ func writeASNsPrefixesAndPeers(t *testing.T, db *Database, ts time.Time) {
 	err = db.UpdatePeerBatch(map[string]PeerUpdate{
 		testV4PeerIP: {
 			PeerIP: testV4PeerIP, PeerASN: 64500,
-			MessageType: "UPDATE", Timestamp: ts,
+			MessageType: "UPDATE", Seen: seen,
 		},
 	})
 	if err != nil {
 		t.Fatalf("UpdatePeerBatch: %v", err)
 	}
 
-	err = db.RecordPeering(64500, 64501, ts)
+	err = db.RecordPeering(64500, 64501, seen)
 	if err != nil {
 		t.Fatalf("RecordPeering: %v", err)
 	}
@@ -192,7 +194,10 @@ func TestLiveCountsSeededFromDatabaseAtStartup(t *testing.T) {
 
 	ts := time.Date(2026, 1, 2, 3, 4, 5, 0, time.UTC)
 
-	err = db.GetOrCreateASNBatch(map[int]time.Time{64500: ts, 64501: ts, 64502: ts})
+	seen := SeenTimes{First: ts, Last: ts}
+
+	err = db.GetOrCreateASNBatch(
+		map[int]SeenTimes{64500: seen, 64501: seen, 64502: seen})
 	if err != nil {
 		t.Fatalf("GetOrCreateASNBatch: %v", err)
 	}
diff --git a/internal/database/database.go b/internal/database/database.go
index 16425e9..270d7d1 100644
--- a/internal/database/database.go
+++ b/internal/database/database.go
@@ -903,13 +903,14 @@ func (d *Database) UpdatePrefixesBatch(prefixes map[string]time.Time) error {
 	return nil
 }
 
-// newASN returns a new ASN record first and last seen at timestamp, with the
-// handle and description from the AS info lookup when it knows the number.
-func newASN(number int, timestamp time.Time) ASN {
+// newASN returns a new ASN record first seen at seen.First and last seen at
+// seen.Last, with the handle and description from the AS info lookup when it
+// knows the number.
+func newASN(number int, seen SeenTimes) ASN {
 	asn := ASN{
 		ASN:       number,
-		FirstSeen: timestamp,
-		LastSeen:  timestamp,
+		FirstSeen: seen.First,
+		LastSeen:  seen.Last,
 	}
 
 	// Look up ASN info
@@ -921,12 +922,12 @@ func newASN(number int, timestamp time.Time) ASN {
 	return asn
 }
 
-// upsertASN updates the last_seen time of ASN number with the given
+// upsertASN sets the last_seen time of ASN number to seen.Last with the given
 // statements, inserting the ASN when it is new. It reports whether it inserted
 // it.
 func upsertASN(
 	ctx context.Context, selectStmt, updateStmt, insertStmt *sql.Stmt,
-	number int, timestamp time.Time,
+	number int, seen SeenTimes,
 ) (bool, error) {
 	var (
 		asn                 ASN
@@ -937,7 +938,7 @@ func upsertASN(
 		&description, &asn.FirstSeen, &asn.LastSeen)
 	if err == nil {
 		// ASN exists, update last_seen
-		_, err = updateStmt.ExecContext(ctx, timestamp, number)
+		_, err = updateStmt.ExecContext(ctx, seen.Last, number)
 		if err != nil {
 			return false, fmt.Errorf("failed to update ASN %d: %w", number, err)
 		}
@@ -950,7 +951,7 @@ func upsertASN(
 	}
 
 	// ASN doesn't exist, create it
-	asn = newASN(number, timestamp)
+	asn = newASN(number, seen)
 
 	_, err = insertStmt.ExecContext(ctx, asn.ASN, asn.Handle,
 		asn.Description, asn.FirstSeen, asn.LastSeen)
@@ -962,7 +963,7 @@ func upsertASN(
 }
 
 // GetOrCreateASNBatch creates or updates multiple ASNs in a single transaction
-func (d *Database) GetOrCreateASNBatch(asns map[int]time.Time) error {
+func (d *Database) GetOrCreateASNBatch(asns map[int]SeenTimes) error {
 	if len(asns) == 0 {
 		return nil
 	}
@@ -1004,9 +1005,9 @@ func (d *Database) GetOrCreateASNBatch(asns map[int]time.Time) error {
 
 	var newASNs int
 
-	for number, timestamp := range asns {
+	for number, seen := range asns {
 		inserted, err := upsertASN(ctx, selectStmt, updateStmt, insertStmt,
-			number, timestamp)
+			number, seen)
 		if err != nil {
 			return err
 		}
@@ -1075,7 +1076,7 @@ func (d *Database) GetOrCreateASN(number int, timestamp time.Time) (*ASN, error)
 	}
 
 	// ASN doesn't exist, create it with ASN info lookup
-	asn = newASN(number, timestamp)
+	asn = newASN(number, SeenTimes{First: timestamp, Last: timestamp})
 
 	_, err = tx.Exec("INSERT INTO asns "+
 		"(asn, handle, description, first_seen, last_seen) "+
@@ -1182,7 +1183,7 @@ func (d *Database) RecordAnnouncement(announcement *Announcement) error {
 }
 
 // RecordPeering records a peering relationship between two ASNs.
-func (d *Database) RecordPeering(asA, asB int, timestamp time.Time) error {
+func (d *Database) RecordPeering(asA, asB int, seen SeenTimes) error {
 	// Validate ASNs
 	if asA <= 0 || asB <= 0 {
 		return fmt.Errorf("%w: asA=%d, asB=%d", errInvalidASN, asA, asB)
@@ -1218,12 +1219,12 @@ func (d *Database) RecordPeering(asA, asB int, timestamp time.Time) error {
 	if exists {
 		_, err = tx.Exec(
 			"UPDATE peerings SET last_seen = ? WHERE as_a = ? AND as_b = ?",
-			timestamp, asA, asB)
+			seen.Last, asA, asB)
 	} else {
 		_, err = tx.Exec(`
 			INSERT INTO peerings (id, as_a, as_b, first_seen, last_seen)
 			VALUES (?, ?, ?, ?, ?)`,
-			generateUUID().String(), asA, asB, timestamp, timestamp)
+			generateUUID().String(), asA, asB, seen.First, seen.Last)
 	}
 
 	if err != nil {
@@ -1301,11 +1302,11 @@ func (d *Database) UpdatePeerBatch(peers map[string]PeerUpdate) error {
 
 		if exists {
 			_, err = updateStmt.ExecContext(ctx, update.PeerASN,
-				update.Timestamp, update.MessageType, update.PeerIP)
+				update.Seen.Last, update.MessageType, update.PeerIP)
 		} else {
 			_, err = insertStmt.ExecContext(ctx,
 				generateUUID().String(), update.PeerIP, update.PeerASN,
-				update.Timestamp, update.Timestamp, update.MessageType)
+				update.Seen.First, update.Seen.Last, update.MessageType)
 		}
 
 		if err != nil {
diff --git a/internal/database/database_internal_test.go b/internal/database/database_internal_test.go
index cd82917..a24f25e 100644
--- a/internal/database/database_internal_test.go
+++ b/internal/database/database_internal_test.go
@@ -615,10 +615,12 @@ func TestBatchWriteDuringCheckpoint(t *testing.T) {
 	})
 
 	ts := time.Now().UTC()
+	seen := SeenTimes{First: ts, Last: ts}
+
 	for i := range contentionIterations {
-		asns := map[int]time.Time{
-			i % contendedASNCount:                   ts,
-			(i % contendedASNCount) + asnSecondBand: ts,
+		asns := map[int]SeenTimes{
+			i % contendedASNCount:                   seen,
+			(i % contendedASNCount) + asnSecondBand: seen,
 		}
 
 		err := db.GetOrCreateASNBatch(asns)
@@ -747,7 +749,8 @@ func TestBatchWriteWaitsForAnalyze(t *testing.T) {
 
 	db, messages := newDatabaseWithLockMessages(t)
 	ctx := context.Background()
-	asns := map[int]time.Time{lockTestASN: time.Now().UTC()}
+	now := time.Now().UTC()
+	asns := map[int]SeenTimes{lockTestASN: {First: now, Last: now}}
 
 	// A stored AS gives ANALYZE a table to analyze and statistics to write.
 	err := db.GetOrCreateASNBatch(asns)
@@ -1663,6 +1666,48 @@ func TestUpdatePrefixesBatchKeepsFirstSeen(t *testing.T) {
 	}
 }
 
+// TestUpdatePeerBatchStoresTheEarliestAndLatestTimesOfANewPeer writes a new
+// peer whose updates span 5 seconds. Its row is first seen at the earliest time
+// and last seen at the latest.
+func TestUpdatePeerBatchStoresTheEarliestAndLatestTimesOfANewPeer(
+	t *testing.T,
+) {
+	t.Parallel()
+
+	db, err := New(&config.Config{StateDir: t.TempDir()}, logger.New())
+	if err != nil {
+		t.Fatalf("failed to create database: %v", err)
+	}
+	defer func() { _ = db.Close() }()
+
+	first := time.Date(2026, 1, 2, 3, 4, 5, 0, time.UTC)
+	last := first.Add(5 * time.Second)
+
+	err = db.UpdatePeerBatch(map[string]PeerUpdate{
+		testPeerIP: {
+			PeerIP: testPeerIP, PeerASN: 64500, MessageType: "UPDATE",
+			Seen: SeenTimes{First: first, Last: last},
+		},
+	})
+	if err != nil {
+		t.Fatalf("UpdatePeerBatch: %v", err)
+	}
+
+	var firstSeen, lastSeen time.Time
+
+	err = db.db.QueryRowContext(t.Context(),
+		"SELECT first_seen, last_seen FROM bgp_peers WHERE peer_ip = ?",
+		testPeerIP).Scan(&firstSeen, &lastSeen)
+	if err != nil {
+		t.Fatalf("reading peer %s: %v", testPeerIP, err)
+	}
+
+	if !firstSeen.Equal(first) || !lastSeen.Equal(last) {
+		t.Errorf("peer %s: first seen %s, last seen %s; want %s, %s",
+			testPeerIP, firstSeen, lastSeen, first, last)
+	}
+}
+
 // TestUpsertLiveRouteBatchWritesInKeyOrder writes new routes of two peers out
 // of key order, the last one a second announcement of the first, and checks
 // that the rows were inserted in key order, peer then prefix (each new row's id
diff --git a/internal/database/interface.go b/internal/database/interface.go
index 2f5f8ac..1c49b10 100644
--- a/internal/database/interface.go
+++ b/internal/database/interface.go
@@ -34,7 +34,7 @@ type Stats struct {
 type Store interface {
 	// ASN operations
 	GetOrCreateASN(number int, timestamp time.Time) (*ASN, error)
-	GetOrCreateASNBatch(asns map[int]time.Time) error
+	GetOrCreateASNBatch(asns map[int]SeenTimes) error
 
 	// Prefix operations
 	GetOrCreatePrefix(prefix string, timestamp time.Time) (*Prefix, error)
@@ -44,7 +44,7 @@ type Store interface {
 	RecordAnnouncement(announcement *Announcement) error
 
 	// Peering operations
-	RecordPeering(asA, asB int, timestamp time.Time) error
+	RecordPeering(asA, asB int, seen SeenTimes) error
 
 	// Statistics
 	GetStats() (Stats, error)
diff --git a/internal/database/models.go b/internal/database/models.go
index 5392a4c..8797ae7 100644
--- a/internal/database/models.go
+++ b/internal/database/models.go
@@ -122,12 +122,35 @@ type LiveRouteDeletion struct {
 	IPVersion int
 }
 
-// PeerUpdate represents parameters for updating a peer
+// SeenTimes is the earliest and the latest time one batch of updates saw an AS,
+// a peer or a peering. A row the batch adds is stored first seen at First and
+// last seen at Last; a row already stored keeps its first_seen and has its
+// last_seen set to Last.
+type SeenTimes struct {
+	First time.Time
+	Last  time.Time
+}
+
+// Add makes t the earliest time of s when it is earlier than First, and the
+// latest when it is later than Last. The zero SeenTimes holds no time yet, so
+// the first Add sets both.
+func (s *SeenTimes) Add(t time.Time) {
+	if s.First.IsZero() || t.Before(s.First) {
+		s.First = t
+	}
+
+	if s.Last.IsZero() || t.After(s.Last) {
+		s.Last = t
+	}
+}
+
+// PeerUpdate represents parameters for updating a peer. PeerASN and
+// MessageType are those of the peer's latest update.
 type PeerUpdate struct {
 	PeerIP      string
 	PeerASN     int
 	MessageType string
-	Timestamp   time.Time
+	Seen        SeenTimes
 }
 
 // ASNWHOISUpdate contains WHOIS data for updating an ASN record.
diff --git a/internal/routewatch/app_integration_internal_test.go b/internal/routewatch/app_integration_internal_test.go
index 8cb2474..f467126 100644
--- a/internal/routewatch/app_integration_internal_test.go
+++ b/internal/routewatch/app_integration_internal_test.go
@@ -152,7 +152,7 @@ func (m *mockStore) RecordAnnouncement(_ *database.Announcement) error {
 }
 
 // RecordPeering mock implementation
-func (m *mockStore) RecordPeering(asA, asB int, _ time.Time) error {
+func (m *mockStore) RecordPeering(asA, asB int, _ database.SeenTimes) error {
 	m.mu.Lock()
 	defer m.mu.Unlock()
 
@@ -396,16 +396,16 @@ func (m *mockStore) DeleteLiveRoutesOfPeer(_ string) (int, error) {
 }
 
 // GetOrCreateASNBatch mock implementation
-func (m *mockStore) GetOrCreateASNBatch(asns map[int]time.Time) error {
+func (m *mockStore) GetOrCreateASNBatch(asns map[int]database.SeenTimes) error {
 	m.mu.Lock()
 	defer m.mu.Unlock()
 
-	for number, timestamp := range asns {
+	for number, seen := range asns {
 		if _, exists := m.ASNs[number]; !exists {
 			m.ASNs[number] = &database.ASN{
 				ASN:       number,
-				FirstSeen: timestamp,
-				LastSeen:  timestamp,
+				FirstSeen: seen.First,
+				LastSeen:  seen.Last,
 			}
 			m.ASNCount++
 		}
@@ -766,7 +766,9 @@ const (
 	callClose      = "close"
 )
 
-func (s *closeOrderStore) GetOrCreateASNBatch(asns map[int]time.Time) error {
+func (s *closeOrderStore) GetOrCreateASNBatch(
+	asns map[int]database.SeenTimes,
+) error {
 	s.record(callWrite)
 
 	return s.Store.GetOrCreateASNBatch(asns)
diff --git a/internal/routewatch/ashandler.go b/internal/routewatch/ashandler.go
index 3991c80..d82b9f8 100644
--- a/internal/routewatch/ashandler.go
+++ b/internal/routewatch/ashandler.go
@@ -229,19 +229,21 @@ func (h *ASHandler) flushBatch() {
 		return
 	}
 
-	// Process ASNs first (deduped)
-	asnMap := make(map[int]time.Time)
+	// The earliest and the latest time the batch saw each AS. The batch holds
+	// several updates for an AS, from many peers, so a new AS is stored first
+	// seen at the earliest of them and last seen at the latest.
+	asns := make(map[int]database.SeenTimes)
 	for _, op := range batch {
-		if existing, ok := asnMap[op.number]; !ok || op.timestamp.After(existing) {
-			asnMap[op.number] = op.timestamp
-		}
+		seen := asns[op.number]
+		seen.Add(op.timestamp)
+		asns[op.number] = seen
 	}
 
 	// Process all ASNs in a single batch transaction
-	err := h.db.GetOrCreateASNBatch(asnMap)
+	err := h.db.GetOrCreateASNBatch(asns)
 	if err != nil {
 		h.logger.Error("Failed to process ASN batch",
-			"error", err, "count", len(asnMap))
+			"error", err, "count", len(asns))
 	}
 
 	h.mu.Lock()
diff --git a/internal/routewatch/ashandler_internal_test.go b/internal/routewatch/ashandler_internal_test.go
new file mode 100644
index 0000000..8510a7a
--- /dev/null
+++ b/internal/routewatch/ashandler_internal_test.go
@@ -0,0 +1,44 @@
+package routewatch
+
+import (
+	"testing"
+
+	"git.eeqj.de/sneak/routewatch/internal/logger"
+)
+
+// TestASHandlerStoresTheEarliestAndLatestTimesOfANewAS handles two updates
+// whose path carries an AS the database does not hold yet, the second 5
+// seconds after the first, in one batch into a real database. The AS is stored
+// first seen at the time of the first update and last seen at the time of the
+// second.
+func TestASHandlerStoresTheEarliestAndLatestTimesOfANewAS(t *testing.T) {
+	t.Parallel()
+
+	db := newTestDatabase(t)
+
+	// Built without NewASHandler's flush goroutine, so the test flushes itself.
+	h := &ASHandler{db: db, logger: logger.New()}
+
+	first := peerAnnouncement(testPeerIP, testV4Prefix)
+	second := peerAnnouncement(testPeerIP, testV4Prefix)
+	second.ParsedTimestamp = first.ParsedTimestamp.Add(secondUpdateAfter)
+
+	h.HandleMessage(first)
+	h.HandleMessage(second)
+	h.flushBatch()
+
+	asn, _, err := db.GetASDetails(testASNA)
+	if err != nil {
+		t.Fatalf("GetASDetails(%d): %v", testASNA, err)
+	}
+
+	if !asn.FirstSeen.Equal(first.ParsedTimestamp) {
+		t.Errorf("first_seen of AS%d = %s, want %s", testASNA,
+			asn.FirstSeen, first.ParsedTimestamp)
+	}
+
+	if !asn.LastSeen.Equal(second.ParsedTimestamp) {
+		t.Errorf("last_seen of AS%d = %s, want %s", testASNA,
+			asn.LastSeen, second.ParsedTimestamp)
+	}
+}
diff --git a/internal/routewatch/batchwrite_internal_test.go b/internal/routewatch/batchwrite_internal_test.go
index 605a8d9..b9ce48d 100644
--- a/internal/routewatch/batchwrite_internal_test.go
+++ b/internal/routewatch/batchwrite_internal_test.go
@@ -66,7 +66,7 @@ func (s *blockingStore) UpsertLiveRouteBatch(routes []*database.LiveRoute) error
 	return nil
 }
 
-func (s *blockingStore) GetOrCreateASNBatch(asns map[int]time.Time) error {
+func (s *blockingStore) GetOrCreateASNBatch(asns map[int]database.SeenTimes) error {
 	s.waitForRelease()
 	s.mu.Lock()
 	defer s.mu.Unlock()
@@ -96,10 +96,12 @@ func (s *blockingStore) DeleteLiveRoutesOfPeer(peerIP string) (int, error) {
 	return s.mockStore.DeleteLiveRoutesOfPeer(peerIP)
 }
 
-func (s *blockingStore) RecordPeering(asA, asB int, ts time.Time) error {
+func (s *blockingStore) RecordPeering(
+	asA, asB int, seen database.SeenTimes,
+) error {
 	s.waitForRelease()
 
-	return s.mockStore.RecordPeering(asA, asB, ts)
+	return s.mockStore.RecordPeering(asA, asB, seen)
 }
 
 func (s *blockingStore) waitForRelease() {
diff --git a/internal/routewatch/peerhandler.go b/internal/routewatch/peerhandler.go
index 7854695..6fb3278 100644
--- a/internal/routewatch/peerhandler.go
+++ b/internal/routewatch/peerhandler.go
@@ -37,8 +37,8 @@ const (
 
 // PeerHandler tracks BGP peers from UPDATE messages using batched operations.
 // It maintains a queue of peer updates and periodically flushes them to the database
-// in batches to improve performance. The handler deduplicates peer updates within
-// each batch, keeping only the most recent update for each peer IP address.
+// in batches to improve performance. The handler writes one row per peer IP
+// address for each batch, with the earliest and the latest time of its updates.
 type PeerHandler struct {
 	db     database.Store
 	logger *logger.Logger
@@ -227,31 +227,28 @@ func (h *PeerHandler) flushBatch() {
 		return
 	}
 
-	// Deduplicate by peer IP, keeping the latest update for each peer
-	peerMap := make(map[string]peerUpdate)
+	// The earliest and the latest time the batch saw each peer, with the peer
+	// AS and message type of its latest update. The batch holds several
+	// updates for a peer, so a new peer is stored first seen at the earliest of
+	// them and last seen at the latest.
+	peers := make(map[string]database.PeerUpdate)
 	for _, update := range batch {
-		existing, ok := peerMap[update.peerIP]
-		if !ok || update.timestamp.After(existing.timestamp) {
-			peerMap[update.peerIP] = update
+		peer, ok := peers[update.peerIP]
+		if !ok || update.timestamp.After(peer.Seen.Last) {
+			peer.PeerIP = update.peerIP
+			peer.PeerASN = update.peerASN
+			peer.MessageType = update.messageType
 		}
-	}
 
-	// Convert to database format
-	dbPeerMap := make(map[string]database.PeerUpdate)
-	for peerIP, update := range peerMap {
-		dbPeerMap[peerIP] = database.PeerUpdate{
-			PeerIP:      update.peerIP,
-			PeerASN:     update.peerASN,
-			MessageType: update.messageType,
-			Timestamp:   update.timestamp,
-		}
+		peer.Seen.Add(update.timestamp)
+		peers[update.peerIP] = peer
 	}
 
 	// Process all peers in a single batch transaction
-	err := h.db.UpdatePeerBatch(dbPeerMap)
+	err := h.db.UpdatePeerBatch(peers)
 	if err != nil {
 		h.logger.Error("Failed to process peer batch",
-			"error", err, "count", len(dbPeerMap))
+			"error", err, "count", len(peers))
 	}
 
 	h.mu.Lock()
diff --git a/internal/routewatch/peerhandler_internal_test.go b/internal/routewatch/peerhandler_internal_test.go
new file mode 100644
index 0000000..23e351f
--- /dev/null
+++ b/internal/routewatch/peerhandler_internal_test.go
@@ -0,0 +1,59 @@
+package routewatch
+
+import (
+	"testing"
+
+	"git.eeqj.de/sneak/routewatch/internal/database"
+	"git.eeqj.de/sneak/routewatch/internal/logger"
+)
+
+// peerBatchStore keeps the peers of the last UpdatePeerBatch call. The
+// database has no read of the peer table, so the peer handler's test checks
+// what the handler writes.
+type peerBatchStore struct {
+	*mockStore
+
+	peers map[string]database.PeerUpdate
+}
+
+func (s *peerBatchStore) UpdatePeerBatch(
+	peers map[string]database.PeerUpdate,
+) error {
+	s.peers = peers
+
+	return nil
+}
+
+// TestPeerHandlerWritesTheEarliestAndLatestTimesOfANewPeer handles two updates
+// from one peer, the second 5 seconds after the first, in one batch. The peer
+// handler writes the peer first seen at the time of the first update and last
+// seen at the time of the second.
+func TestPeerHandlerWritesTheEarliestAndLatestTimesOfANewPeer(t *testing.T) {
+	t.Parallel()
+
+	store := &peerBatchStore{mockStore: newMockStore()}
+
+	// Built without NewPeerHandler's flush goroutine, so the test flushes
+	// itself.
+	h := &PeerHandler{db: store, logger: logger.New()}
+
+	first := peerAnnouncement(testPeerIP, testV4Prefix)
+	second := peerAnnouncement(testPeerIP, testV4Prefix)
+	second.ParsedTimestamp = first.ParsedTimestamp.Add(secondUpdateAfter)
+
+	h.HandleMessage(first)
+	h.HandleMessage(second)
+	h.flushBatch()
+
+	seen := store.peers[testPeerIP].Seen
+
+	if !seen.First.Equal(first.ParsedTimestamp) {
+		t.Errorf("first_seen of peer %s = %s, want %s", testPeerIP,
+			seen.First, first.ParsedTimestamp)
+	}
+
+	if !seen.Last.Equal(second.ParsedTimestamp) {
+		t.Errorf("last_seen of peer %s = %s, want %s", testPeerIP,
+			seen.Last, second.ParsedTimestamp)
+	}
+}
diff --git a/internal/routewatch/peeringhandler.go b/internal/routewatch/peeringhandler.go
index f304082..b1cddc4 100644
--- a/internal/routewatch/peeringhandler.go
+++ b/internal/routewatch/peeringhandler.go
@@ -42,10 +42,11 @@ type PeeringHandler struct {
 	db     database.Store
 	logger *logger.Logger
 
-	// In-memory AS path tracking
+	// In-memory AS path tracking: each path, JSON-encoded, with the earliest
+	// and the latest time an update carried it.
 	mu           sync.Mutex
-	asPaths      map[string]time.Time // key is JSON-encoded AS path
-	droppedPaths int                  // paths dropped because the map was full
+	asPaths      map[string]database.SeenTimes
+	droppedPaths int // paths dropped because the map was full
 	// writing is how many paths processPeerings took from asPaths and has
 	// not finished writing the peerings of.
 	writing int
@@ -64,7 +65,7 @@ func NewPeeringHandler(db database.Store, logger *logger.Logger) *PeeringHandler
 	h := &PeeringHandler{
 		db:      db,
 		logger:  logger,
-		asPaths: make(map[string]time.Time),
+		asPaths: make(map[string]database.SeenTimes),
 		stopCh:  make(chan context.Context, 1),
 		done:    make(chan struct{}),
 	}
@@ -118,16 +119,18 @@ func (h *PeeringHandler) HandleMessage(msg *ristypes.RISMessage) {
 	key := string(pathJSON)
 
 	h.mu.Lock()
-	if _, exists := h.asPaths[key]; exists {
-		// Already tracked: refresh its timestamp.
-		h.asPaths[key] = timestamp
-	} else if len(h.asPaths) >= maxTrackedPaths {
+	defer h.mu.Unlock()
+
+	seen, exists := h.asPaths[key]
+	if !exists && len(h.asPaths) >= maxTrackedPaths {
 		// Map is full; drop this new path and count it.
 		h.droppedPaths++
-	} else {
-		h.asPaths[key] = timestamp
+
+		return
 	}
-	h.mu.Unlock()
+
+	seen.Add(timestamp)
+	h.asPaths[key] = seen
 }
 
 // ProcessPeeringsNow triggers immediate processing of all accumulated AS
@@ -190,7 +193,7 @@ func (h *PeeringHandler) processPeerings() {
 	// released, so the map never grows past a single interval's traffic.
 	h.mu.Lock()
 	paths := h.asPaths
-	h.asPaths = make(map[string]time.Time)
+	h.asPaths = make(map[string]database.SeenTimes)
 	h.writing = len(paths)
 	dropped := h.droppedPaths
 	h.mu.Unlock()
@@ -204,9 +207,13 @@ func (h *PeeringHandler) processPeerings() {
 		low, high int
 	}
 
-	peerings := make(map[peeringKey]time.Time)
+	// The earliest and the latest time an update carried each peering. Several
+	// paths, each carried at several times, can hold a peering, so a new
+	// peering is stored first seen at the earliest of them and last seen at the
+	// latest.
+	peerings := make(map[peeringKey]database.SeenTimes)
 
-	for pathJSON, timestamp := range paths {
+	for pathJSON, pathSeen := range paths {
 		var path []int
 
 		err := json.Unmarshal([]byte(pathJSON), &path)
@@ -233,10 +240,11 @@ func (h *PeeringHandler) processPeerings() {
 			}
 
 			key := peeringKey{low: low, high: high}
-			// Update timestamp if this is newer
-			if existing, ok := peerings[key]; !ok || timestamp.After(existing) {
-				peerings[key] = timestamp
-			}
+
+			seen := peerings[key]
+			seen.Add(pathSeen.First)
+			seen.Add(pathSeen.Last)
+			peerings[key] = seen
 		}
 	}
 
@@ -244,8 +252,8 @@ func (h *PeeringHandler) processPeerings() {
 	start := time.Now()
 	successCount := 0
 
-	for key, ts := range peerings {
-		err := h.db.RecordPeering(key.low, key.high, ts)
+	for key, seen := range peerings {
+		err := h.db.RecordPeering(key.low, key.high, seen)
 		if err != nil {
 			h.logger.Error("Failed to record peering",
 				"as_a", key.low,
diff --git a/internal/routewatch/peeringhandler_internal_test.go b/internal/routewatch/peeringhandler_internal_test.go
index b11737a..75bc05a 100644
--- a/internal/routewatch/peeringhandler_internal_test.go
+++ b/internal/routewatch/peeringhandler_internal_test.go
@@ -31,12 +31,14 @@ type recordingStore struct {
 	calls int
 }
 
-func (r *recordingStore) RecordPeering(asA, asB int, ts time.Time) error {
+func (r *recordingStore) RecordPeering(
+	asA, asB int, seen database.SeenTimes,
+) error {
 	r.mu.Lock()
 	r.calls++
 	r.mu.Unlock()
 
-	return r.mockStore.RecordPeering(asA, asB, ts)
+	return r.mockStore.RecordPeering(asA, asB, seen)
 }
 
 func (r *recordingStore) callCount() int {
@@ -52,7 +54,7 @@ func newTestHandler(db database.Store) *PeeringHandler {
 	return &PeeringHandler{
 		db:      db,
 		logger:  logger.New(),
-		asPaths: make(map[string]time.Time),
+		asPaths: make(map[string]database.SeenTimes),
 	}
 }
 
@@ -220,10 +222,10 @@ func TestPeeringHandlerCapDropsAndCounts(t *testing.T) {
 	existing := pathKey(t, testASNA, testASNB)
 
 	h.mu.Lock()
-	h.asPaths[existing] = now
+	h.asPaths[existing] = database.SeenTimes{First: now, Last: now}
 
 	for i := 0; len(h.asPaths) < maxTrackedPaths; i++ {
-		h.asPaths[strconv.Itoa(i)] = now
+		h.asPaths[strconv.Itoa(i)] = database.SeenTimes{First: now, Last: now}
 	}
 	h.mu.Unlock()
 
@@ -253,11 +255,53 @@ func TestPeeringHandlerCapDropsAndCounts(t *testing.T) {
 	}
 
 	h.mu.Lock()
-	gotTS := h.asPaths[existing]
+	gotSeen := h.asPaths[existing]
 	h.mu.Unlock()
 
-	if !gotTS.Equal(refreshed) {
-		t.Fatalf("existing path timestamp not refreshed: want %v, got %v",
-			refreshed, gotTS)
+	if !gotSeen.Last.Equal(refreshed) {
+		t.Fatalf("existing path last seen not refreshed: want %v, got %v",
+			refreshed, gotSeen.Last)
+	}
+}
+
+// TestPeeringHandlerStoresTheEarliestAndLatestTimesOfANewPeering handles two
+// updates whose path carries a peering the database does not hold yet, the
+// second 5 seconds after the first, in one run into a real database. The
+// peering is stored first seen at the time of the first update and last seen
+// at the time of the second.
+func TestPeeringHandlerStoresTheEarliestAndLatestTimesOfANewPeering(
+	t *testing.T,
+) {
+	t.Parallel()
+
+	db := newTestDatabase(t)
+	h := newTestHandler(db)
+
+	first := peerAnnouncement(testPeerIP, testV4Prefix)
+	second := peerAnnouncement(testPeerIP, testV4Prefix)
+	second.ParsedTimestamp = first.ParsedTimestamp.Add(secondUpdateAfter)
+
+	h.HandleMessage(first)
+	h.HandleMessage(second)
+	h.ProcessPeeringsNow()
+
+	peers, err := db.GetASPeers(testASNA)
+	if err != nil {
+		t.Fatalf("GetASPeers(%d): %v", testASNA, err)
+	}
+
+	if len(peers) != 1 || peers[0].ASN != testASNB {
+		t.Fatalf("peers of AS%d = %+v, want AS%d alone", testASNA, peers,
+			testASNB)
+	}
+
+	if !peers[0].FirstSeen.Equal(first.ParsedTimestamp) {
+		t.Errorf("first_seen of peering AS%d-AS%d = %s, want %s", testASNA,
+			testASNB, peers[0].FirstSeen, first.ParsedTimestamp)
+	}
+
+	if !peers[0].LastSeen.Equal(second.ParsedTimestamp) {
+		t.Errorf("last_seen of peering AS%d-AS%d = %s, want %s", testASNA,
+			testASNB, peers[0].LastSeen, second.ParsedTimestamp)
 	}
 }
diff --git a/internal/routewatch/prefixhandler.go b/internal/routewatch/prefixhandler.go
index 329651e..e7f62f9 100644
--- a/internal/routewatch/prefixhandler.go
+++ b/internal/routewatch/prefixhandler.go
@@ -347,8 +347,19 @@ func (h *PrefixHandler) flushBatch() {
 
 	lastUpdates := make(map[prefixAndPeer]prefixUpdate)
 
+	// Each prefix the batch names, announced or withdrawn, with the earliest
+	// timestamp among all of its updates, not only each peer's last one: the
+	// prefix tables store only first_seen, written when the prefix is new and
+	// never changed after.
+	prefixesToUpdate := make(map[string]time.Time)
+
 	for _, update := range batch {
 		lastUpdates[prefixAndPeer{update.prefix, update.peer}] = update
+
+		seen, exists := prefixesToUpdate[update.prefix]
+		if !exists || update.timestamp.Before(seen) {
+			prefixesToUpdate[update.prefix] = update.timestamp
+		}
 	}
 
 	// Collect routes to upsert and delete
@@ -357,16 +368,7 @@ func (h *PrefixHandler) flushBatch() {
 		routesToDelete []database.LiveRouteDeletion
 	)
 
-	// Collect unique prefixes to update
-	prefixesToUpdate := make(map[string]time.Time)
-
 	for _, update := range lastUpdates {
-		// Track prefix for both announcements and withdrawals
-		seen, exists := prefixesToUpdate[update.prefix]
-		if !exists || update.timestamp.After(seen) {
-			prefixesToUpdate[update.prefix] = update.timestamp
-		}
-
 		// An announcement is stored when its path gives an origin, or when it
 		// ends in an AS set of several members: that route is stored with
 		// origin 0 (none). An announcement with an empty path is not stored.
diff --git a/internal/routewatch/prefixhandler_internal_test.go b/internal/routewatch/prefixhandler_internal_test.go
index 12aeb9d..30c6433 100644
--- a/internal/routewatch/prefixhandler_internal_test.go
+++ b/internal/routewatch/prefixhandler_internal_test.go
@@ -26,6 +26,10 @@ const (
 	testV6Prefix = "2001:db8:1::/48"
 )
 
+// secondUpdateAfter is how long after the first update the tests of first_seen
+// and last_seen send the second, in the same batch.
+const secondUpdateAfter = 5 * time.Second
+
 // TestPrefixHandlerStoresPrefixesTheIPLookupFinds runs announcements and
 // withdrawals through the prefix handler into a real database and looks the
 // addresses up. The prefixes are written the way the feed sends them: IPv6
@@ -83,6 +87,49 @@ func TestPrefixHandlerStoresPrefixesTheIPLookupFinds(t *testing.T) {
 	}
 }
 
+// TestPrefixHandlerStoresANewPrefixFirstSeenAtItsEarliestUpdate announces a
+// prefix the database does not hold yet twice in one batch, the second time 5
+// seconds after the first, through the prefix handler into a real database. The
+// prefix is stored first seen at the time of the first announcement, whether
+// the two come from two peers or from one, and the IP lookup answers with that
+// time.
+func TestPrefixHandlerStoresANewPrefixFirstSeenAtItsEarliestUpdate(
+	t *testing.T,
+) {
+	t.Parallel()
+
+	const otherPeerIP = "2001:db8:ffff::2"
+
+	tests := []struct {
+		name                  string
+		firstPeer, secondPeer string
+	}{
+		{name: "two peers", firstPeer: testPeerIP, secondPeer: otherPeerIP},
+		{name: "one peer", firstPeer: testPeerIP, secondPeer: testPeerIP},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			t.Parallel()
+
+			first := peerAnnouncement(tt.firstPeer, testV4Prefix)
+			second := peerAnnouncement(tt.secondPeer, testV4Prefix)
+			second.ParsedTimestamp = first.ParsedTimestamp.Add(secondUpdateAfter)
+			db := handleBatches(t, [][]*ristypes.RISMessage{{first, second}})
+
+			info, err := db.GetIPInfo("192.0.2.1")
+			if err != nil {
+				t.Fatalf("GetIPInfo(192.0.2.1): %v", err)
+			}
+
+			if !info.FirstSeen.Equal(first.ParsedTimestamp) {
+				t.Errorf("first_seen of %s = %s, want %s", testV4Prefix,
+					info.FirstSeen, first.ParsedTimestamp)
+			}
+		})
+	}
+}
+
 // TestPrefixHandlerAppliesEachPeersLastUpdateInABatch runs updates for one
 // prefix through the prefix handler into a real database. All updates carry the
 // same timestamp, as updates within one second of the feed do. Within a batch,