 Vushmgir then proceeded to fortress, but was shortly surprised attacked by the Buyid ruler Hasan, and was forced to flee back to the Samanid border, where he once again requested aid from the Samanid ruler Nuh I, who once again sent an army to aid him.This time the conquest went successful; in 947, Vushmgir managed to defeat al-Hasan and expel him from Tabaristan, gaining control over the region once again.In 948 Hasan (who since the Buyids' entrance into Baghdad in 945 had used the title "Rukn al-Dawla") invaded Tabaristan and Gorgan and took them from Voshmgir.