Complex sentence: Aixa was first married to Muhammed XI, and after his death in 1455, she was married by his successor Said to his heir, Abu l-Hasan Ali, likely in an attempt to make peace between the rival factions of the dynasty.
Split into simpler sentences: Aixa was first married to Muhammed XI; after his death in 1455, she was married by his successor Said to his heir, Abu l-Hasan Ali. Her second marriage was likely an attempt to make peace between the rival factions of the dynasty.