I'll start with the backstory.
1) Origins of Volgastan
The origins of Volgastan date back to the 5th Century BC, when Greek traders and colonists penetrated the Don River and crossed over to the Volga. Several colonies were established with the soul purpose of trading with the Scythians. By the 1st Century BC, the Scythians had absorbed the Greeks. Many of the semi-nomadic people were attracted to the cities and by Greek living. By the 1st Century AD, a Greco-Scythian civilization thrived on the banks of the Volga. Of the cities lining the Volga and the Don, the city of Hyrcanopolis was the grandest.
The actual name of the city has been lost to history. Being built on islands of the Volga River Delta, historians have christened the city Hyrcanopolis, after the Hyrcanian Ocean, which the Ancient Greeks believed existed with the Caspian Sea as its southern most reach. Sailors from Hyrcanopolis traded across the sea, and when they stumbled upon the norther boundaries of the Persian Empire, quickly learned the Hyrcanian Ocean was no ocean at all. Though the knowledge did reach the West, many Greek and Roman maps still displayed the Caspian as a giant gulf.
Hyrcanopolis grew into an important northern terminal on the Silk Road. As well as bringing in goods from the Far East and the Steppe, the Volga River and Caspian Sea produced their own exports. Among these were sturgeon, Caspian Seals, and other exotic goods. Furs as well as silks flowed out of the city and into the Roman Empire. The Greco-Scythians had contact with two mightiest cities of their day; Rome and Chang’an. In the 2nd Century, a Chinese expedition reached the north shores of the Black Sea, establishing contact with early Volgastan.
Greco-Scythian civilization faced a down fall between the 2nd and 5th Centuries, with first the Goths invading their lands. These northern barbarians were bad enough, but by the 4th Century, they were being driven out by the Huns. The Hunic hordes pillaged and burned cities along the Volga and Don Rivers, leaving nothing but ash in their wake. Greco-Scythians retreated southward, taking refuge in the Volgan Delta, as well as taking flight on the Caspian Sea. The art of war learned from the Greeks did little against nomadic cavalry. Once the Huns passed, civilization spread north again, slowly reclaiming lost territory. This was put to an abrupt end by a new invasion of nomads, which included Alans, Khazars and most importantly, the Bulgars.