The siege of Constantinople in 626 by the Sassanid Persians and Avars, aided by large numbers of allied Slavs, ended in a strategic victory for the Byzantines. The failure of the siege saved the empire from collapse, and, combined with other victories achieved by Emperor Heraclius (r. 610641) the previous year and in 627, enabled Byzantium to regain its territories and end the destructive RomanPersian Wars by enforcing a treaty with borders status quo c. 590.