The province of Tabaristan in Persia lay to the south of the Caspian Sea. The province was so named because almost every citizen carried with him an axe-Tabar.
Tabaristan was conquered by the Muslims during the caliphate of Umar. After the conquest of Rayy, the Muslim commander Nuaim b Muqarrin sent an expedition to Tabaristan under the command of his brother Suwaid b Muqarrin. Suwaid proceeded to the city of Qumas in the first instance. The people of Qumas did not choose to fight. On the approach of the Muslims, they opened the gates of their city, and submitted to the Muslim rule on the usual terms. From Qumas tile Muslim forces proceeded to Jurjan. It was an important town on the main highway to Merv. The Persian garrison under the command of Rozban offered feeble resistance which was soon overcome by the Muslims. The citizens surrendered and accepted submission to the Muslim rule on the usual terms.
From Jurjan the Muslim force marched to Dehistan. When the people of Dehistan learnt that Jurjan had surrendered to the Muslims, they also found safety in submitting to the Muslim rule. Peace was made on the citizens agreeing to pay tribute.
From Dehistan the victorious Muslim force marched to Amul. The Persian garrison at Amul was commanded by Sipehdar, a seasoned warrior. The city was strongly fortified. Sipehdar accordingly decided to defend the city. The Persians shut themselves in the city and closed the gates. The Muslims invested the city. The siege dragged on for some time and the Persians began to suffer from the lack of water and provisions. Sipehdar opened negotiations with the Muslim commander. Peace was made on the Persians agreeing to the usual terms. With the fall of Amul, the Muslims became the masters of the whole of Tabaristan.