Alp Arslan was the son of Chaghri and nephew of Tughril, the founding Sultans of the Seljuk Empire. His grandfather was Mikail, who in turn was the son of the warlord Seljuk. He was the father of numerous children, including Malik-Shah I and Tutush I.[3] It is unclear who the mother or mothers of his children were. He was known to have been married at least twice. His wives included the widow of his uncle Tughril, a Kara-Khanid princess known as Aka Khatun, and the daughter or niece of Bagrat IV of Georgia (who would later marry his vizier, Nizam al-Mulk).[4] One of Seljuk's other sons was the Turkic chieftain Arslan Isra'il, whose son, Kutalmish, contested his nephew's succession to the sultanate. Alp Arslan's younger brothers Suleiman ibn Chaghri and Qavurt were his rivals. Kilij Arslan, the son and successor of Suleiman ibn Kutalmish (Kutalmish's son, who would later become Sultan of Rûm), was a major opponent of the Franks during the First Crusade and the Crusade of 1101.[5]