The origin of the Danes remains undetermined, but several ancient historical documents and texts refer to them and archaeology has revealed and continues to reveal insights into their culture, beliefs, organization and way of life. The Danes first appear in written history in the 6th century with references in Jordanes' Getica (551 AD), by Procopius, and by Gregory of Tours. They spoke Old Norse (dǫnsk tunga), which the Danes shared with the people in Norway and Sweden and later in Iceland. In his description of Scandza, Jordanes says that the Dani were of the same stock as the Suetidi ("Swedes") and expelled the Heruli and took their lands. The Old English poems Widsith and Beowulf, as well as works by later Scandinavian writers (notably by Saxo Grammaticus, provide some of the original written references to the Danes. According to the 12th-century author Sven Aggesen, the mythical King Dan gave his name to the Danes.