Sogdia
ancient civilization of an Iranian people and a province of the Achaemenid Empire
Sogdia was a historical region (6th century BCE to 11th century CE) in Central Asia, the northernmost province of the Persian Empire and of the kingdom Alexander the Great established in the region after conquering the Persians. It lay north of the Oxus River (now called Amu Darya) and the Romans called it Transoxania (literally Beyond the Oxus). Sogdia was the center of the overland Silk Roads, and many of the quintessentially "Silk Road" cities lie in the region.

Historically, the Sogdians (the Indo-Iranian group who occupied the region) were never politically unified. Rather, their cities competed with each other for mercantile benefits, much like the city states in Renaissance Italy, while the people were all the same.
The area is a fertile plain while much of the nearby land consists of mountains and deserts. Borders have changed over the centuries; today most of it is in Uzbekistan, but parts of the historical region extend into what are now Kazakhstan, Tajikistan (Sughd region) and Afghanistan.