Susa ( SOO-sə) was an ancient city in the lower Zagros Mountains about 250 km (160 mi) east of the Tigris, between the Karkheh and Dez Rivers in Iran. It represents the current city of Shush, located on the site of ancient Susa. One of the most important cities of the Ancient Near East, Susa served as the capital of Elam and the winter capital of the Achaemenid Empire, and remained a strategic centre during the Parthian and Sasanian periods.