The Battle of Merv
Yazdjurd crossed the Oxus and sought refuge with the Khaqan of Farghana. After the death of Umar, the Persians revolted against the Muslims and a greater part of Persia was lost to the Muslims. Availing of this opportunity, Yazdjurd with the help of a Turkish force reoccupied Merv.

Conspiracy against Yazdjurd
In spite of the reoccupation of Merv, Yazdjurd was not able to have a firm hold on administration. Neizak Tarkhan was the strongest and the most powerful chief in Khurasan, and when Yazdjurd wanted to win him over to his side, Neizak demanded that Yazdjurd should marry one of his daughters to him. Yazdjurd considered such demand to be an affront, and he gave a rude reply to Neizak. Thereupon Neizak led a force against Yazdjurd. Mahrweih the Governor of Merv was won over by Neizak. When the battle was at its thickest, and the forces of the Shah appeared to have the upper hand, Mahrweih with a large detachment crossed over to the side of Neizak. That turned the tide of the battle. The forces loyal to Yazdjurd fought heroically, but they were outnumbered, and were soon overpowered.