 With the aid of Amr, Rustam was allowed to return to his domains in Mazandaran.The Caliph al-Mu'tadid (r. 892–902) was forced to acknowledge the reality of the Saffarids' domination in the East, and reached a "modus vivendi" with them, perhaps hoping, according to Hugh N. Kennedy, to harness them in a partnership analogous to that which the Tahirids had enjoyed in previous decades.Consequently, the Saffarids were recognized in their possession of Khurasan and eastern Persia as well as Fars, while the Abbasids were to exercise direct control over Jibal, Ray and Isfahan.