Complex sentence: The double identification of Hygelac as either "Dane" or "Geat" is not surprising, since "Dane" seems to have been used as a generic term for Scandinavians (cf. Danish toungue and East Dane).
Split into simpler sentences: The double identification of Hygelac as either "Dane" or "Geat" is not surprising. Because "Dane" seems to have been used as a generic term for Scandinavians (cf. Danish toungue and East Dane).