Sarai Batu (Old Sarai, Sarai-al-Maqrus, also transcribed as Saraj or Saray) was a capital city of the Golden Horde and one of the largest cities of the medieval world, with a population estimated by the 2005 Britannica at 600,000.
The city of Sarai Batu (or Sarai Berke) was likely located on the Akhtuba channel of the lower Volga River near contemporary village Selitrennoye in Kharabalinsky District, Astrakhan Oblast, Russia, about 120 km north from Astrakhan. Mongol ruler Batu Khan is credited with building the city in the mid-1240s on the site of Saqsin (which may have itself been built on the site of the Khazar capital, Atil).
Sarai Batu's importance stems from the fact that Rus princes had to obtain patents of authority (yarlyk) from the khan in Sarai. This both encouraged competition between princes and solidified the Golden Horde's control over the area.
New Sarai, called Sarai-al-Jadid on coins, is located at modern Kolobovka, formerly Tsarev, an archeological site also on the Akhtuba channel 85 km east of Volgograd. The bishops of Krutitsy resided in Tsarev from 1261 to 1454. It had probably succeeded Sarai Batu as the capital of the Golden Horde by the mid-1300's.
Either one or both cities were destroyed several times. Tamerlane destroyed New Sarai around 1395, Meñli I Giray of Crimea destroyed New Sarai around 1502. The final destruction happened after 1556 when Ivan IV of Russia conquered Astrakhan Khanate.
In 1623-24, merchant Fedot Afanasyevich Kotov took a journey to Persia. He gave the following account of the lower Volga: Here by the river Akhtuba stands the Golden Horde. The khan's court, palaces, and courts, and mosques are all made of stone. But now all these buildings are being dismantled and the stone is being taken to Astrakhan. Most likely, this was a description of New Sarai.