Sassanians

   Dynasty that ruled Persia (q.v.) from 226-651, with its capital at Ctesiphon; Byzantium's (q.v.) long-time eastern foe until Herakleios (q.v.) conquered the Sassanian state in 628. Ardashir I made its official religion Zoroastrianism (q.v.). His successor Shapur I (240-270) was one of Rome's (q.v.) most dangerous enemies, and subsequent kings Chosroes I and Chosroes II (qq.v.) posed grave threats to Byzantium. Under Yazdgird III, the last Sassanian king, the Arabs (q.v.) advanced into Persia, destroying Persian resistance in 642. Yazdgird III remained a fugitive at large for another 10 years before he was killed, bringing to an end a dynasty that ruled Persia for more than four centuries.