Following the defeat and death of his father Kilij Arslan fighting against Ridwan of Aleppo at the battle of Khabur river in 1107,[1] Mesud lost the throne in favor of his brother Malik Shah.

Emperor Manuel I Komnenos persuaded Mesud I to attack Thoros II and demand his submission to the Sultan's suzerainty.

[4] In the year 603 AE (1154) once again the Byzantine emperor Manuel sought to stoke Masud and he sent him twice the amount of treasure as previously, saying: «Quench the burning of my heart toward the Armenian people, destroy their fortresses, and exterminate them.» So the sultan came to Anazarbus with many troops, but he was unable to accomplish anything.

When they had crossed the gate, the Brothers (the Knights Templar), as though sent by God, swooped upon them at that place and slaughtered all of them, including their chief.

When he returned and saw what had unfolded everyone thanked God, for they had been defeated without the use of weapons and without a physical battle.When he died, Mesud was succeeded by his son Kilij Arslan II.