Muhammad I Tapar

Muhammad I Tapar rebelled against his half-brother Sultan Barkiyaruq, claiming the sultanate with support from the Abbasid Caliph al-Mustazhir. This began a prolonged civil war that divided the Seljuk Empire.

Muhammad I Tapar's forces captured the city of Isfahan, the Seljuk capital, from Barkiyaruq's control. This victory strengthened his position and forced Barkiyaruq to retreat to western Persia.

Muhammad I Tapar agreed to a partition treaty with Barkiyaruq, dividing the Seljuk Empire. Muhammad gained control over the eastern provinces, including Khorasan and Transoxiana, while Barkiyaruq retained the title of sultan and western domains.

Following Barkiyaruq's death, Muhammad I Tapar became the sole sultan of the Seljuk Empire. He reunified the empire and began campaigns to restore Seljuk authority in the west, including against the Crusader states.

Muhammad I Tapar launched a major military campaign against the Crusader states in Syria, besieging the city of Edessa. Although he failed to capture the city, the campaign demonstrated renewed Seljuk military power and pressured the Crusaders.

Muhammad I Tapar died in Isfahan, possibly from illness. His death led to another succession crisis, with his son Mahmud II claiming the sultanate but facing challenges from his uncle Ahmad Sanjar, who eventually became the dominant Seljuk ruler.