Anglo-Saxon and Irish sources suggest that the Danish invasion of England after 865 was led by three brothers called Ingvar (i.e. Ivar), Ubbe and Halfdan who, judging from the Irish "Cogad Gáedel re Gallaib", were sons of a Ragnall (Ragnar or a similar name). Björn is not mentioned in this context, but later Norman tradition suggests that he may have been a brother. According to William of Jumièges he died in Frisia, which also had an association with the invaders of England. Ubbe is sometimes labeled the "Frisian Jarl" and the invaders are occasionally called Scaldingi (men from Schelde). The kingships of Björn is at times historically problematic since it is not supported by older sources and presents insurmountable chronological inconsistencies.