Neolithic farmers established settlements in the Zagros mountains, in the west of modern Iran, from 6000 BC. From around 2700 BC the southwestern region of Khuzestan was inhabited by Elamite societies, a formative influence on the first Persian empire, established by Cyrus the Great in 550 BC. His Achaemenian dynasty lasted until around 320 BC and was ruled from Persepolis. Persia was subsequently controlled by the Parthian and Sassanian dynasties, during which the Zoroastrian religion took hold. Arabians arriving in the 7th century AD spread the Islamic faith. Their armies defeated the Sassanians at Nahavand in 641, ushering in a period of control by Arab caliphs and, from the 10th century, Seljuk Turks. Persia came under the control of Ghengis Khan’s Mongol armies in the 1220s and was then ruled by Timur from 1370.