The Amu Darya (also called the Amu, Amo River, and historically known by its Latin name or Greek ) 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. Names In classical antiquity, the river was known as the in Latin and () in Greek — a clear derivative of Vakhsh, the name of the largest tributary of the river. In Vedic Sanskrit, the river is also referred to as (). The Brahmanda Purana refers to the river as which means an eye. The Avestan texts too refer to the River as Yakhsha/Vakhsha (and Yakhsha Arta ("upper Yakhsha") referring to the Jaxartes/Syr Darya twin river to Amu Darya). In Middle Persian sources of the Sasanian period the river is known as (lit. 'good river'). The name Amu is said to have come from the medieval city of Āmul, (later, Chahar Joy/Charjunow, and now known as Türkmenabat), in modern Turkmenistan, with Darya being the Persian word for "lake". Medieval Arabic and Islamic sources call the river Jayhoun (; also Jaihun, Jayhoon, or Dzhaykhun) which is derived from Gihon, the biblical name for one of the four rivers of the Garden of Eden. River Amu Darya passes through one of the world's highest deserts. As the river Gozan Western travelers in the 19th century mentioned that one of the names by which the river was known in Afghanistan was Gozan, and that this name was used by Greek, Mongol, Chinese, Persian, Jewish, and Afghan historians. However, this name is no longer used. "Hara (Bokhara) and to the river of Gozan (that is to say, the Amu, (called the Oxus by Europeans )) ..." "the Gozan River is the River Balkh, i.e. the Oxus or the Amu Darya ..." "... and were brought into Halah (modern day Balkh), and Habor