 Their character and elevated location indicate they belonged to a temporary Bronze Age settlement (1800-500 BC), by people who visited the island for seasonal hunting and fishing.The first permanent settlement dates back to the late Germanic Iron Age (400-800 AD).A small burial ground containing some 15 graves on the north-eastern part of the island known as "Ormknös" is possibly the remains of a small settlement pre-dating Birka by less than a century.