In 1729, Nader Shah, a chieftain and military genius from Khorasan, successfully drove out and conquered the Pashtun invaders. He subsequently took back the annexed Caucasian territories which were divided among the Ottoman and Russian authorities by the ongoing chaos in Iran. During the reign of Nader Shah, Iran reached its greatest extent since the Sassanid Empire, reestablishing the Iranian hegemony all over the Caucasus, as well as other major parts of the west and central Asia, and briefly possessing what was arguably the most powerful empire at the time.