Complex sentence: Many of the pretenders in these kingdoms sought refuge with Birger, and among them the Birkebeiner chieftains Eystein Meyla and Sverre Sigurdsson who were Birgit's kinsmen.
Split into simpler sentences: Many of the pretenders in these kingdoms sought refuge with Birger. Among them were the Birkebeiner chieftains Eystein Meyla and Sverre Sigurdsson who were Birgit's kinsmen.