These swamp ruins were part of the Illefarn Empire, but time claimed them once the Illefarn Empire disappeared. Their magic was still in place, as one of the ruins contained a portal, which was linked with Arvahn, another Illefarn ruin.
After the battle with the King of Shadows in West Harbor, Daeghun found a silver shard. Since he did not want to keep it nor to drop it, he hid it in the ruins to keep it safe. However, bladelings and duergar attacked the village in 1374 DR, so Daeghun tasked the Kalach-Cha to retrieve it. The shard lay in the first ruin, and the Kalach-Cha could not open the second ruin. Bevil heard it could not be opened and that a wizard that tried to get in there never returned.
The portal was activated once the Kalach-Cha completed the four rituals at Arvahn. This allowed the Kalach-Cha to come back to West Harbor and see it destroyed, as well as the final statue that was required to complete the fifth part of the ritual. Once most of the shards had been gained, the Kalach-Cha needed to use the portal to come to the place where the Blade of Gith had been destroyed, as the King of Shadows' power prevented the the Kalach-Cha from going directly to the village.