By: Mir M.Hosseini
In a meeting at the imperial palace in Tisfun, the Iranian noblemen suggested moving the capital from Tisfun to Estakhr for security reasons. King Yazdgerd 3 first accepted the proposal but he changed his mind later. The Iranian army had just been defeated and Derafsh Kaviani had been seized by the Caliph forces. Yazdgerd 3 did not take the Arab invasion very seriously; therefore he tasted next defeat in Tisfun the next year. His next defeat happened near Helvan right before the great victory of Caliphates over the Iranian army in Nahavand.
Yazdgerd 3 was assassinated in Marv after retreating to the greater Khorasan. One of the main reasons behind Sassanid defeat is said to be disappointment of the infantry which were mostly from the working class. The Sassanid regime was a class based society and was suffering from internal power struggles alongside devastation left from years of war with Romans. On the contrary, the Caliph propaganda was very promising; heaven on earth and brotherhood of men sounded familiar to those of Mazdak thus; during the wars the Iranian infantry units did not show much resistance.