Sogdia (/ˈsɒɡdiə/) or Sogdiana was an ancient Iranian civilization between the Amu Darya and the Syr Darya rivers, and in present-day Uzbekistan, Turkmenistan, Tajikistan, Kazakhstan, and Kyrgyzstan. Sogdiana was also a province of the Achaemenid Empire, and listed on the Behistun Inscription of Darius the Great. Sogdiana was first conquered by Cyrus the Great, the founder of the Achaemenid Empire, and then was annexed by the Macedonian ruler Alexander the Great in 328 BC. It would continue to change hands under the Seleucid Empire, the Greco-Bactrian Kingdom, the Kushan Empire, the Sasanian Empire, the Hephthalite Empire, the Western Turkic Khaganate, and the Muslim conquest of Transoxiana.
The Sogdian city-states, although never politically united, were centered on the city of Samarkand. Sogdian, an Eastern Iranian language, is no longer spoken. However, a descendant of one of its dialects, Yaghnobi, is still spoken by the Yaghnobis of Tajikistan. It was widely spoken in Central Asia as a lingua franca and served as one of the First Turkic Khaganate's court languages for writing documents.
