sentences:  This period saw the rapid Islamization of the native population of Tabaristan.Although the majority accepted Sunni Islam, Shi'ism also spread, especially in Amul and the neighbouring areas of Astarabad and Gurgan.Thus, in 864, a Zaydi Alid, Hasan ibn Zayd, was invited to Tabaristan, and with support from the Daylamites took over control of the province.