Amu Darya

The Amu Darya, historically known as the Oxus, is a major river in Central Asia which flows through Afghanistan, Tajikistan, Turkmenistan, and Uzbekistan. 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. However, today the Amu Darya does not reach the Aral Sea, and its mouth is in a dried-up area, of what was once 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.

In classical antiquity, the river was known as the Ōxus in Latin and Ὦξος (Ôxos) in Greek — a clear derivative of Vakhsh, the name of the largest tributary of the river. In Sanskrit texts, the river is also referred to as Vakṣu (वक्षु). The Brahmanda Purana refers to the river as Chaksu (चक्षु) which means 'an eye' in sanskrit. 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 Wehrōd (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 Daryā being the Persian word for 'lake' or 'sea'.

Medieval Arabic and Islamic sources call the river Jeyhoun (Arabic: جَيْحُون, romanized: Jayḥūn), which is derived from Gihon, the biblical name for one of the four rivers of the Garden of Eden. The Amu Darya passes through one of the world's highest deserts.

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 (which is Pesh Habor or Peshawar), and Hara (which is Herat), and to the river Gozan (which is the Ammoo, also called Jehoon) ..."

The river has a total length of 2,400 kilometres (1,500 mi), and its drainage basin covers 534,739 square kilometres (206,464 sq mi), providing a mean discharge of about 97.4 cubic kilometres (23.4 cu mi) of water per year. The river is navigable for over 1,450 kilometres (900 mi). All of the water comes from the high mountains in the south where annual precipitation can be over 1,000 mm (39 in). Even before large-scale irrigation began, high summer evaporation meant that not all of this discharge reached the Aral Sea – though there is some evidence the large Pamir glaciers provided enough meltwater for the Aral to overflow during the 13th and 14th centuries. Since the end of the 19th century, there have been four different claimants as the true source of the Oxus:

Flows through: Afghanistan, Tajikistan, Turkmenistan.

River data from Wikidata (CC0); lengths normalised to a common unit.