Complex sentence: As in many places that saw Mandinka migrations, many of Guinea-Bissau's native populations were dominated or assimilated with resisters being sold into slavery via the trans-Sahara trade routes to Arab buyers.
Split into simpler sentences: As in many places that saw Mandinka migrations, much of Guinea-Bissau's native population was dominated or assimilated. Resisters being sold into slavery via the trans-Sahara trade routes to Arab buyers.