Province of ancient Persia.
It was centred in the fertile valley of the Zeravshan River, in modern 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 0441; 250 BC as part of the Bactrian kingdom (see Bactria ) and fell to invading northern tribes in the 2nd century BC. It prospered as a centre of Islamic civilization, especially under the S 0101; m 0101; nid dynasty (9th10th centuries AD), until the Mongol invasion of the 13th century. See also Bukhara .