The Amu Darya (also called the Amu, Amo River, and historically known by its Latin name Oxus or Greek Ὦξος) is a major river in Central Asia and Afghanistan. Rising in the Pamir Mountains, north of the Hindu Kush, the Amu Darya is formed by the confluence of the Vakhsh and Panj rivers, in the Tigrovaya Balka Nature Reserve on the border between Afghanistan and Tajikistan, and flows from there north-westwards into the southern remnants of the Aral Sea. In its upper course, the river forms part of Afghanistan's northern border with Tajikistan, Uzbekistan, and Turkmenistan. In ancient history, the river was regarded as the boundary of Greater Iran with "Turan", which roughly corresponded to present-day Central Asia. The Amu Darya has a flow of about 70 cubic kilometres per year on average.