Kathir participated in Abu Yazid Khalid's invasion of Kerman and Fars in 917, in which the latter was defeated and killed.
Following the defeat, Kathir returned to Sistan with a portion of Abu Yazid Khalid's army, and was recognized as amir in Zarang on May 19, 917.
With the support of the local 'ayyars, he defeated an army sent by Badr ibn 'Abdallah, the governor of Fars and Kerman, to retake the province.
He released prisoners captured in the battle with Badr's army and offered tribute to Baghdad; the caliphal government accepted this gesture.
Just as peace had been established, however, Kathir was assassinated as the result of a conspiracy involving an 'ayyar leader, the commander of his Indian troops, and an officer named Ahmad ibn Qudam.