Sogdiana (sŏgdēā`nə), part of the ancient Persian Empire in central Asia between the Oxus (Amu Darya) and Jaxartes (Syr Darya) rivers. Corresponding to the later emirate of Bukhara and region of Samarkand, it was also known as Transoxiana. Sogdiana, though often a possession of other countries, had its own language, culture, and trading centers. Ancient Sogdian was a Persian language written in an Aramaic script. Sogdiana was a satrapy under Darius I. Conquered 329 B.C. by Alexander the Great, it fell (7th cent. A.D.) to the Arabs and was a center of Islamic culture until 9th cent. Controlled (13th–15th cent.) by the Mongols, the region was later ruled by the Uzbeks and the emirs of Bukhara (see Bukhara, emirate of Bukhara, emirate of, former state, central Asia, in Turkistan , in the Amu Darya River basin. Part of ancient Sogdiana , it was ruled (A.D. 709–874) by the Umayyad Arabs and played an important role under the Samanid dynasties (875–1000).
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Sogdiana

Ancient country of Central Asia. It was centred in the fertile valley of the Zeravshan River, in present-day Uzbekistan. It became a satrapy of the Achaemenian dynasty under Darius I in the 6th century BC and was conquered by Alexander the Great in the 4th century. It asserted its independence from the Seleucid dynasty c. 250 BC as part of the kingdom of Bactria and fell to invading northern tribes in the 2nd century BC. It prospered as a centre of Islamic civilization, especially under the Samanid dynasty (9th–10th centuries AD), until the Mongol invasion of the 13th century. See also Bukhara.