The Harpy Tombs
On occasion in the eastern archipelago, when the clans move around the isles they come across the remnants of a previous clan. The burial sites, the shrines to the gods and sometimes even the great halls intact, but not a soul in sight. Though sometimes one might interpret these sites as merely the temporary settlement of an otherwise itinerant sailing clan, in other cases the mass of goods and the clear effort put into erecting the many structures of the now abandoned settlement gives cause to question this assumption.
Local legend states that on occasion, a particularly aggressive harpy coven may move to attack an isolated or weak clan. Maneaters with no concept of art or aesthetics, the harpies will leave valuables behind and as creatures of the storm will not value the shelter built by the Tescarana either. Thus a harpy attack would leave an intact and fully furnished, but empty settlement.
A few will willingly seek out the Harpy Tombs, knowing that while the harpies often lair somewhere close to their victims and their range may bring them to the site again, even an average Tescarana clan may hold a fortune in murex dye in particular.
Historical Basis
These harpy tombs exist in the murky waters between legend and reality. While most locals will agree that yes, there are harpy covens in the Eastern Archipelago, an abandoned island settlement is rarely taken as proof of harpy activity in the area. In many cases, clan warfare, Red Sails activity, or simply the clan moving to another island are the actual causes. Nevertheless, only a fool would entirely discount the tales of the Harpy Tombs.
Ghost town are always creepy to me, particularly as they're not really a thing in England. Ghost towns created (potentially) by harpies are even creepier. I like that no one really knows the truth.