Yazdegerd III (Last Sassanid Emperor)

Yazdegerd III was the last ruler of the Sassanid Persian Empire, which had been one of the two superpowers of the ancient world alongside the Byzantine Empire. He came to the throne in 632 CE, the same year the Prophet Muhammad ﷺ died, inheriting an empire already weakened by decades of war with Byzantium. The Muslim expansion into Iraq began almost immediately after the Prophet's death, and Yazdegerd faced a series of catastrophic military defeats. The Battle of al-Qadisiyyah (15-16 AH / 636-637 CE) was the decisive blow — the Persian general Rustam Farrokhzad was killed and the Persian army routed. Yazdegerd fled from his capital Ctesiphon (al-Mada'in) as the Muslims advanced. He spent the next fifteen years fleeing eastward, seeking help from various local rulers and from the Tang dynasty of China, never able to rebuild a sufficient force. In 32 AH (651 CE), while in Merv (in modern Turkmenistan/Central Asia), he was assassinated by a local miller, reportedly during a robbery, ending his destitute years of flight. His death marked the formal end of the Sassanid Empire, though Persia's conversion to Islam was a gradual process over the following century.