Complex sentence: One theory proposes that it was developed in Frisia and later spread to England, while another holds that Scandinavians introduced runes to England, where the fuþorc was modified and exported to Frisia.
Split into simpler sentences: One theory proposes that it was developed in Frisia and later spread to England. Another holds that runes were introduced by Scandinavians to England where the fuþorc was modified and exported to Frisia.