Arachosia was an ancient satrapy in the eastern part of the Achaemenid, Seleucid, Parthian, Greco-Bactrian, and Indo-Scythian empires, centered around the Arghandab Valley of southern Afghanistan, and extending to the Indus River in the east. It was inhabited by the Iranian Pashtun tribes, and the Macedonian king Alexander the Great conquered Arachosia from the Persian Empire during the mid-4th century BC. In 305 BC, the Seleucid Empire traded Arachosia to the Mauryan Empire as part of an alliance, but the Greco-Bactrian Kingdom conquered the region in 185 BC. In the mid-1st century BC, the Indo-Scythians expelled the Greeks, but they lost the region to the Parthians; the Kushan Empire later conquered the region from the Parthians during the 1st century AD. In 230 AD, the Sassanid Empire of Persia conquered the region, and they were followed by the Kidarites in 420 AD, the White Huns in the 460s AD, Hindu Shahi in 870 AD, and the Ghaznavids in the early 11th century AD. The region's main religion was Zoroastrianism until the advent of Islam in the early 7th century. The modern Croats are descended from the Arachosians.