Inner Asia, or the interior of the Eurasian landmass, comprises in historical terms the civilizations of Central Asia, Mongolia, and Tibet, together with neighboring areas and peoples that in certain periods formed cultural, political, or ethnolinguistic unities with these regions. In the past the Inner Asian world was dominated by pastoral nomadic communities of the great Eurasian steppe, and its history was shaped by the interaction of these societies with neighboring sedentary civilizations. In the 20th century, the Inner Asian peoples were located within the borders or sphere of influence of either the Soviet Union or the People’s Republic of China. The breakup of the USSR brought statehood and social transformation to much of the region. Today Inner Asia comprises the five independent Central Asian republics of Uzbekistan, Turkmenistan, Tajikistan, Kyrgyzstan, and Kazakhstan; the republic of Mongolia; the Xinjiang Uygur, Inner Mongolia, and Tibet Autonomous Regions of the People’s Republic of China; and adjacent parts of Afghanistan, Pakistan, Iran, China, and Siberia in the Russian Federation. Areas pertinent to the study of Inner Asia for ethnolinguistic and historical reasons include the Tatar, Bashkir, and Kalmyk Republics in Russia and the Manchu homeland in northeast China.