diff --git a/scripts-dev/complement.sh b/scripts-dev/complement.sh
index da2cf6ae67..9d08c154da 100755
--- a/scripts-dev/complement.sh
+++ b/scripts-dev/complement.sh
@@ -65,4 +65,4 @@ if [[ -n "$1" ]]; then
 fi
 
 # Run the tests!
-go test -v -tags synapse_blacklist,msc2946,msc3083,msc2716,msc2403 -count=1 $EXTRA_COMPLEMENT_ARGS ./tests -run TestBackfillingHistory
+go test -v -tags synapse_blacklist,msc2946,msc3083,msc2716,msc2403 -count=1 $EXTRA_COMPLEMENT_ARGS ./tests -run TestBackfillingHistory/parallel/Historical_messages_are_visible_when_already_joined_on_federated_server
diff --git a/synapse/api/constants.py b/synapse/api/constants.py
index 8363c2bb0f..78364100e1 100644
--- a/synapse/api/constants.py
+++ b/synapse/api/constants.py
@@ -196,9 +196,6 @@ class EventContentFields:
     MSC2716_CHUNK_ID = "org.matrix.msc2716.chunk_id"
     # For "marker" events
     MSC2716_MARKER_INSERTION = "org.matrix.msc2716.marker.insertion"
-    MSC2716_MARKER_INSERTION_PREV_EVENTS = (
-        "org.matrix.msc2716.marker.insertion_prev_events"
-    )
 
 
 class RoomTypes:
diff --git a/synapse/storage/databases/main/events.py b/synapse/storage/databases/main/events.py
index 75d01464e0..107d8ad38d 100644
--- a/synapse/storage/databases/main/events.py
+++ b/synapse/storage/databases/main/events.py
@@ -1819,10 +1819,24 @@ class PersistEventsStore:
         # TODO: We should attempt to backfill the insertion event instead
         # of trying to  pack all of the info in the marker event. Otherwise,
         # we need to pack in the insertion_prev_events and insertion_next_chunk_id.
+        # GET /_matrix/federation/v1/event/{eventId}
 
-        # insertion_event_id = event.content.get(
-        #     EventContentFields.MSC2716_MARKER_INSERTION
+        insertion_event_id = event.content.get(
+            EventContentFields.MSC2716_MARKER_INSERTION
+        )
+
+        # We will trust that the application service sending the marker event is
+        # also the one that knows about the insertion event
+        # insertion_event_origin = get_domain_from_id(event.sender)
+        # m_ev = await self.federation_client.get_event(
+        #     [insertion_event_origin],
+        #     insertion_event_id,
+        #     outlier=True,
+        #     timeout=10000,
         # )
+        # _auth_and_persist_events
+        # handle_new_client_event
+
         # insertion_prev_event_ids = event.content.get(
         #     EventContentFields.MSC2716_MARKER_INSERTION_PREV_EVENTS
         # )