Early settlements included the Scythians during the 9th century BC. Following the Scythians, Iranian Medes came to dominate the area to the south of the Aras river. The Medes forged a vast empire between 900 and 700 BC, which was integrated into the Achaemenid Empire around 550 BC. The area was conquered by the Achaemenids leading to the spread of Zoroastrianism.