Sarai was the name of possibly two cities near the lower Volga, that served successively as the effective capitals of the Cuman–Kipchak Confederation and the Golden Horde, a Turco-Mongol kingdom which ruled much of Northwestern Asia and Eastern Europe, in from the 10th through the 14th century. There is considerable disagreement among scholars about the correspondence between specific archaeological sites and the various references to سرای‎, (Sarāy); سرای باتو‎ ; سرای برکه‎, ; سرای الجدید‎, ; and سرای المحروسه‎ in the historical sources.

The Volga is the longest river in Europe. Situated in Russia, it flows through Central Russia to Southern Russia and into the Caspian Sea. The Volga has a length of 3,531 km (2,194 mi), and a catchment area of 1,360,000 km2 (530,000 sq mi). It is also Europe's largest river in terms of average discharge at delta – between 8,000 m3/s (280,000 cu ft/s) and 8,500 m3/s (300,000 cu ft/s) – and of drainage basin. It is widely regarded as the national river of Russia. The hypothetical old Russian state, the Rus' Khaganate, arose along the Volga c. 830 AD. Historically, the river served as an important meeting place of various Eurasian civilizations.