Political relationship between Sasanid and Eastern nomadic tribes during Arabs invasion

During Sasanian sovereignty there were some nomadic people who liued in eastern neighborhood of Iran. Seeking for new land and place, those tribes migrated from deserts of central Asia and even from China to west. In their migration course, they encountered sasanian empire. Kushanian, Khiunies, Kidars, Hiatele, and Turles were the most important neighbors of Iran during different periods at the time of Sasanian sovereignty. when Moslem Arabs possessed Iran the relation between them and Iran broke off, although during the post-Islam some of these nations restored their crucial role. From the end of sasanian period, every tawny man appeared hereinafter in " Turu", and the word" Turu" was used for all tawny nations with a convergent common language have been regarded as " Turu. "They include: 1) Taghzghaz (To’uz - Aghuz), 2) Kherkhiz (kirghiz), 3) Kimau, 4) Ghaz (oghuz), Kharlakh (Gharagh-khalakh).