Al-Hasan (who since the Buyids' entrance into Baghdad in 945 has used the title Rukn al-Dawla) had invaded Tabaristan and Gorgan in 948 and taken them from Vushmgir, the second Ziyarid emir.
While al-Hasan supports the Buyids, Vushmgir relies on his Samanid allies.
Tabaristan and Gorgan had changed hands several times until 955, when in a treaty with the Samanids, Rukn al-Daula had promised to leave Vushmgir alone in Tabaristan.
Peace between the two sides did not last long, however; in 958 Vushmgir had briefly occupied Rey, which was Rukn al-Dawla's capital.
Rukn al-Dawla later made a counterattack, temporarily taking Gorgan in 960, then taking both Tabaristan and Gorgan for a short time in 962.
He may have also taken Tabaristan and Gorgan in 966, but did not hold on to them for long.
Vushmgir’s son Bisutun is the governor of Tabaristan.
Upon the death of his father in 967 during a boar-hunting expedition, Bisutun goes to Gorgan to assume power.
His ascension is contested, however, by a Samanid army which had arrived shortly before Vushmgir's death for a joint campaign against the Buyid Rukn al-Daula.
The army commander supports making Bisutun's brother Qabus as ruler of the Ziyarids.
Bisutun now turns to Rukn al-Daula, recognizing the latter's sovereignty in an attempt to gain support.
The Samanid army soon leaves Gorgan, returning to Khurasan, but …
