For example, the 9th-century Annales Bertiniani reveals that Danish Vikings devastated Frisia in 850, and the 12th-century Annales Lindisfarnenses et Dunelmenses states that a Viking force of Danes and Frisians made landfall on the Isle of Sheppey in 855. The same source, and the 10th- or 11th-century Historia de sancto Cuthberto, describe Ubba as  of the Frisians.
For instance, the 9th-century Annales Bertiniani shows that Danish Vikings destroyed Frisia in 850, while the 12th-century Annales Lindisfarnenses et Dunelmenses mentions a Viking force of Danes and Frisians landing on Sheppey Island in 855. The same source, along with the 10th- or 11th-century Historia de sancto Cuthberto, identifies Ubba as a Frisian.