Complex sentence: Some pre-Adamite theorists held that Cain left his family for an inferior tribe described variously as "white Mongols" or that Cain took a wife from one of the inferior pre-Adamite peoples.
Split into simpler sentences: Some Pre-Adamite theorists held that Cain left his family for an inferior tribe described variously as "white Mongols". Pre-Adamites also claimed that Cain took a wife from one of the inferior pre-Adamite peoples.