The early details of the Faroe Islands are often unclear. It is possible that Brendan, an Irish monk, sailed past the islands during his North Atlantic voyage in the 6th century. He saw an 'Island of Sheep' and a 'Paradise of Birds,' which some say could be the Faroes with its dense bird population and sheep. Norsemen settled the Faroe Islands in the 9th century or 10th century. The islands were officially converted to Christianity around the year 1000, and became a part of the Kingdom of Norway in 1035. Norwegian rule on the islands continued until 1380, when the islands became part of the dual Denmark–Norway kingdom, under king Olaf II of Denmark.