Complex sentence: In Islamic, and Oriental cultures, religion either sanctioned polygyny or use of consorts, or had no authority over marriage; monarchs could consequently ensure sufficient numbers of male offspring to confirm the succession.
Split into simpler sentences: In Islamic, and Oriental cultures, religion either sanctioned the practice of polygamy (more specifically, polygyny) or use of consorts, or had no power to sanction marriage. Consequently, monarchs could ensure sufficient numbers of male offspring to confirm the succession.