Evidence of habitation of Öland occurred at least as early as 6000 BC, when there were Stone Age settlements at Alby and other locations on the island. Burial grounds from the Iron Age through the Viking Age are clearly visible at Gettlinge, Hulterstad and other places on the perimeter ridge including stone ships. There are nineteen Iron Age ringforts identified on the island, only one of which, Eketorp, has been completely excavated, yielding over 24,000 artifacts. Around 900 AD, Wulfstan of Hedeby called the island "Eowland", the land of the Eowans: