The Battle on Pyana River took place on August 2, 1377 between the Blue Horde Khan Arapsha (Arab-Shah Muzaffar) and a Russian alliance under Knyaz Ivan Dmitriyevich, made up of the Pereyaslavl, Yaroslavl, Yuryev, Nizhny Novgorod, and Murom principalities.The Russian army, being drunken, was almost entirely routed by small forces of Arapsha, while Ivan Dmitriyevich had drowned together with druzhina and staff. The river's name Pyana, translated as "drunken" from Russian, is derived from those events. The corresponding events are further recorded in the medieval Russian Chronicle On The Slaughter at Pyana River.

According to Rashid-al-Din Hamadani (1247–1318), Genghis Khan's eldest son, Jochi, had nearly 40 sons, of whom he named 14. When he died, they inherited their father's dominions as fiefs under the rule of their brothers, Batu Khan, as supreme khan and Orda Khan, who, although the elder of the two, agreed that Batu enjoyed primacy as the Khan of the Golden Horde (Jochid Ulus).Orda, along with some of his younger brothers, ruled the eastern (left/blue) wing of the Golden Horde while Batu and others ruled the western (right/white) wing of it. These Hordes are known as the "White", "Blue" and "Grey" (Shaybanid) Hordes in Slavic and Persian historiography. The two main divisions are also known as Batu's Ulus (district) and Orda's Ulus.

The relationship between color and direction is a common feature of the Eurasian Steppe amongst Slavic, Turkic, Mongolic and other peoples. Due to the match up of colours, it is likely related to the Four Symbols commonly used in Han China, the blue dragon is associated with the east and the white tiger is associated with the west. The exact history of the relationship between the two however is not precisely known. Under some versions of the traditional system, the east is associated with the left side and the west is associated with the right side because the observer is assumed to be facing the south. Different authors use 'Blue Horde' and 'White Horde' with opposite definitions, which can lead to confusion and has created the need for checking the convention that individual authors use.