Transoxiana or Transoxania (lit. 'Land beyond the Oxus', now called the Amu Darya) is the Latin name for the region and civilization located in lower Central Asia roughly corresponding to eastern Uzbekistan, western Tajikistan, parts of southern Kazakhstan, parts of Turkmenistan and southern Kyrgyzstan. The name was first coined by Alexander the Great in the 4th century BC when Alexander's troops conquered the region. The region may have had a similar Greek name in the days of Alexander the Great, but the earlier name is no longer known. Geographically, it is the region between the rivers Amu Darya to its south and the Syr Darya to its north.

The region of Transoxiana was one of the satrapies (provinces) of the Achaemenid Empire of Persia under the name Sogdia. It was defined within the classical world of Persia to distinguish it from Iran proper, especially its northeastern province of Khorasan, a term originating with the Sasanians, although early Arab historians and geographers tended to subsume the region within the loosely defined term "Khorasan" designating a much larger territory. The territories of Khwarazm, Sogdiana, Chaghaniyan, and Khuttal were located in the southern part of Transoxiana; Chach, Osrushana, and Farghana were located in the northern part.

Historically known in Persian as Farā-rūd (Persian: فرارود, [fæɾɒːˈɾuːd̪] – 'beyond the [Amu] river'), Faro-rɵd (Tajik: Фарорӯд), and Varaz-rüd (Tajik: Варазрӯд), the area had been known to the ancient Iranians as Turan, a term used in the Persian national epic Shahnameh. The corresponding Chinese term for the region is Hezhong (Chinese: 河中地区; Chinese: land between rivers). The Arabic term Mā Warāʾ an-Nahr (Arabic: ما وراء النهر, [ˈmaː waˈraːʔ anˈnahr], which means "what is beyond the [Jayhūn] river") passed into Persian literary usage and stayed on until post-Mongol times.

The name Transoxiana stuck in Western consciousness because of the exploits of Alexander the Great, who extended Greek culture into the region with his invasion in the 4th century BCE. Alexander's successors would go on to found the Greco-Bactrian Kingdom, ushering in a distinct Greek cultural presence within Transoxiana that existed for over two hundred years. The city of Ai-Khanoum on the Oxus in northern Afghanistan remains the only Graeco-Bactrian city found and extensively excavated.

During the Sasanian Empire, it was often called Sogdia, a provincial name taken from the Achaemenid Empire, and used to distinguish it from nearby Bactria.^{[citation needed]}

The Chinese explorer Zhang Qian, who visited the neighbouring countries of Bactria and Parthia along with Transoxiana in 126 BCE, made the first known Chinese report on this region. Zhang Qian identifies Parthia as an advanced urban civilisation that farmed grain and grapes and made silver coins and leather goods. It was ruled successively by Seleucids, the Greco-Bactrian Kingdom, the Parthian Empire and the Kushan Empire before Sassanid rule.^{[citation needed]}

In Sasanian times, the region became a major cultural center due to the wealth of the Northern Silk Road. Sassanid rule was interrupted by the Hephthalite invasion at the end of the 5th century and didn't return to the Sassanids until 565.^{[citation needed]}

Many Persian nobles and landlords escaped to this region after the Muslim conquest of Persia. It was also ruled by Göktürks until the Arab conquest between 705 and 715. The area became known by the Arabic phrase Mā warāʼ al-Nahr "what is beyond the river," sometimes rendered as "Mavarannahr".^{[citation needed]}