Complex sentence: His other sons were Hasan and Ja'far, from whom Hasan became his successor who is known as the eleventh Shiite imam before his son Muhammad al-Mahdi who is the last Shiite imam.
Split into simpler sentences: His other sons were Hasan and Ja'far, from whom Hasan became his successor. He is known as the eleventh Shiite imam before his son Muhammad al-Mahdi who is the last Shiite Imam.