The Amu Darya River, the foremost river in Uzbekistan and Central Asia

Oxus and Jaxartes - ancient names of the Amu Darya and Syr Darya Rivers

The Amu Darya, or Amudarya River, is 2.580 km long and formed by the junction of the Vakhsh and Pandj rivers, which flow out of the Pamir Mountains. It follows a northwesterly course, marking much of the northern border of Afghanistan with Tajikistan, Uzbekistan, and Turkmenistan before flowing through the Karakum desert of Turkmenistan and Uzbekistan, and spilling into the Aral Sea through a broad delta.

The river drains 466.200 sq km. It flows swiftly until it reaches the Karakum where its course braids into several channels. The Amu Darya provides water for irrigation, but this heavy draw on its water has prevented the Amu Darya from replenishing the Aral Sea. The Karakum Canal (800 km long) carries water from the Amu Darya near Kelif across Turkmenistan to Ashgabat and supplements the flow of the Tejen and Murgab rivers.

In ancient times the Amu Darya was called the Oxus and figured importantly in the history of Persia and in the campaigns of Alexander the Great.

The Oxus River was the name that the classical Greek geographers (such as Herodotus) used for the Amu Darya (Darya is Persian for "sea").

The other major river in the area - the Syr Darya, which roughly follows the border between Uzbekistan and Kazakhstan, was called the Jaxartes by the Greeks.

The area beyond the Oxus (from a European or Middle Eastern viewpoint) used to be called Transoxiana (meaning "beyond the Oxus") by the Greeks. Later on, it was referred to as Maworaunnahr (meaning "beyond the river") by the Arabs.