Tabaristan uprising

Tabaristan uprising was a series of rebellions and battles of indigenous Zoroastrian population of Tabaristan against the Abbasid Caliphate, led by local Spahbeds which occurred between 784 and 804. A few years after Spahbed Khurshid's suicide and the annihilation of the Dabuyid dynasty, as dissatisfaction with the actions of the Abbasid caliphs grew, people turned to the Qarinvand dynasty Spahbed, Wandad Hurmuzd and asked him to lead their uprising. After deliberation with Spahbeds of other dynasties such as Baduspanids, Bavandids and Masmughans of Damavand, he accepted people's request. From then Sharwin I was like king of Tabaristan and Wandad was his warlord. On a predetermined day, they raised a great rebellion against the Abbasid caliphate, and the people of Tabaristan and Ruyan attacked the garrisons on this day and killed the Arab soldiers. Historians refer to this day as "the day when Tabaristan was emptied of Caliph's agents" and report that 20,000 people were killed.

After the massacre of Muslims and Caliph's deputy in Tabaristan, the Abbasid Caliphate started a series of battles to recapture Tabaristan. The caliph Al-Mahdi demanded the death of Wandad Hurmuzd and bringing his head to Baghdad, but none of his generals succeeded and finally his heir, Al-Hadi, managed to declare ceasefire and conclude a treaty and bring Wandad to Baghdad with him. Along the route, the Abbasid caliph Al-Mahdi died and Al-Hadi became caliph. Wandad Hurmuzd stayed in Baghdad until the end of Hadi's rule, but finally returned to Tabaristan and another round of the uprising began. Finally, during the caliphate of Harun al-Rashid, with the presence of the Tabaristan princes as hostages in Baghdad, in 804, the Tabaristan rebellions were completely stopped.

Background
After the Muslim conquest of Persia, most of Iran's territories fell under Muslim hands. The Muslim conquerors discriminated and harassed Zoroastrians and forced them to pay Jizya. Among the former Sasanian territories, southern coasts of Caspian Sea sternly stood against Arabs and influence of Islam. These areas were sheltered by the high mountains of Alborz, against the attack of the large army of Arabs while advancing towards Khorasan. At that time, Tabaristan was the most advanced and populated of the regions south of Caspian Sea, and was ruled by a dynasty of House of Ispahbudhan called the Dabuyids. At that time other dynasties also ruled parts of Tabaristan. The presence of these dynasties proves that perhaps the events of Tabaristan were a reflection of an effort to restore the higher ranks of the Sassanid bureaucracy.

Militias dispatched by Arab caliphs attempted many times to invade Tabaristan but none of them was successful and the Dabuyid dynasty more or less withstood their lands against Arabs triumphantly. Until around the year 759, the last Dabuyid ruler, Khurshid, was defeated by Abbasid forces and committed suicide after his lands were captured. Although Khurshid's death caused the Abbasid domination of Tabaristan's plains, and caliph's deputies could collect tax and propagate religion, this didn't mean Abbasids had full control over Tabaristan as other local dynasties such as Karenids, Bavandids and Baduspanids still ruled over mountainous regions of Tabaristan and Ruyan. In the first decades after the conquest, conversion to Islam was a slow process, and especially in rural areas, the majority of residents were Zoroastrians, and the new native Muslims and Arabs lived in scattered communities among this majority.