Sogdia was a historical region 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.
The area is a fertile plain while much of the nearby land is mountains and deserts. Borders have changed over the centuries, and the area has not always been united. Today most of it is in Uzbekistan, but parts of the historical region extend into what are now Kazakhstan, Tajikistan and Afghanistan.
The main language of much of the region is Uzbek (in the Turkic language family) but Tajik (a dialect of Persian) is also fairly widely spoken. The region was part of the Soviet Union so Russian is also common.