Russia (Russian: Россия, Rossiya), officially known as the Russian Republic, is a republic of the Union of Soviet Sovereign Republics which includes territory within Eastern Europe. For all intents and purposes, Russia acts as the core of the entire Soviet Union and has dominates most aspects of the nation (including demographics, linguistics, and politics to name a few). Prior to the separation of Siberia in the 1990s, Russia's territory was the largest within the USSR.
Prior to the 13th Century, the Volga River region was divided between several Slavic and Turkic kingdoms. Unity among these kingdoms would not be achieved until the Mongol Empire moves into the region. It was during this time that Russia adopted the Eastern Orthodox Church and began its expansion east into Siberia. It wouldn't be until the rise of Peter the Great that the Russian Empire would establish itself as a global great power. At its height, the Russian Empire spanned three continents and included a fifth of the world's land area.
By the late 1910s, Russia became the hub for the Bolsheviks during the Russian Civil War. The Russian Soviet Federative Socialist Republic would become one of the founding members of the Soviet Union in 1922. Under Vladimir Lenin's policies of national delimitation, the RSFSR gradually began to shrink as new national republics were established (reaching its final borders in the late 1990s). Throughout the Cold War and beyond, Russia developed as one of the industrial centers of the USSR, which was centered primarily along the Volga River and its tributaries. Under the leadership of Boris Yeltsin, Russia would emerge as a sovereign republic within the USSR and would become one of the founding members of a reformed USSR in 1991. The 1990s would become the height of the Parade of Sovereignties movement, in which many areas demanded equality within the USSR. Tatarstan, Tuva, and Vainakhia were the first to be split off from Russia. The Russian Republic reached its current borders in the late 1990s.
The majority of those living in Russia are ethnic Russians. Finns, Tatars, and Ukrainians make up the largest minorities within Russia. Most Russians adhere to the Eastern Orthodox Church, which has slowly been on the rise since the 1990s. Russia has the largest economy within the Soviet Union and dominated by agriculture and industry. In recent years, Russia has emerged as the "tech capital" of the USSR as many manufacturing of electronics have moved into the area. The cities of Nizhny Novgorod and Tolyatti are the automotive capitals of the USSR, with virtually all the major Soviet car companies centered there. In recent decades, Russia has been politically dominated by the Communist Party in the south (the so-called "Red Belt") and the Democratic Party in the north.