Sasanian Empire

The Sasanian Empire ruled from 224 to 651 AD, founded by Ardashir I after he defeated the last Parthian king, Artabanus IV, at the Battle of Hormozdgan. Its capital was first at Istakhr and, from 226, at Ctesiphon on the Tigris. At its peak the empire covered roughly 3.5 million square kilometers spanning modern-day Iran and Iraq, parts of the Arabian Peninsula, the Caucasus, the Levant, sections of Central Asia and portions of the Indian subcontinent, and it stands as the second-longest-lasting Iranian dynasty, governed through a complex centralized bureaucracy and marked by a revival of Zoroastrianism as state religion. Its cultural influence reached as far as western Europe, East Africa, China and India, and it maintained a long-running military rivalry with the Roman and later Byzantine Empire, climaxing in the devastating Byzantine-Sasanian War of 602 to 628. Weakened by that conflict, the empire fell to the early Muslim conquests carried forward under the Rashidun Caliphate, though several regional Iranian dynasties, including the Dabuyids and Bavandids, continued in its former territory.