Towards the end of the 12th and beginning of the 13th centuries, Serbs and Venetians started to take possession over the territory. The ethnogenesis of the Albanians is uncertain; however the first undisputed mention of Albanians dates back in historical records from 1079 or 1080 in a work by Michael Attaliates, who referred to the Albanoi as having taken part in a revolt against Constantinople. At this point the Albanians were fully Christianized.