The Sassanian dynasty was now on the ropes. The death blow came in 642. The new king of kings, Yazdegerd III, had painstakingly rebuilt his military forces after the terrible losses of the 630s. But his new army went the same way as the old: at the battle of Nahavand tens of thousands of Persians fell beneath Muslim swords, and in the aftermath Yazdegerd’s state collapsed.
