The province of Sistan was the scene of perpetual turmoil following its conquest by Arabs, which lasted until the rise of the Safarids. This descriptive-analytical study seeks to explore the root causes of this turmoil and the incompetence of caliphs’ administration in this province. This study shows that Sistan's instability and decline was not merely provoked by activities of Khawā rij, as the most influential factor in this regard was Bedouin Arabs. Upon conquering this land, they settled in this province, engaging in acts of plundering and looting, which further engendered divisions, tragic conflicts and internecine tribal clashes. It also prepared the ground for the entrance of Khawā rij sect, which was known for its warmongering policies Zonbil and the rebellion of indigenous irregular forces against other sources of instability also contributed to the escalation of turmoil in Sistan. The caliphs’ policy to change this situation was unsuccessful as they narrowed down their focus on one of the above factors. Eventually, their recurring failures in politics resulted in the rise of Ayā rā n among the same native forces, which finally ended the caliphs’ rule and the tumult in Sistan.