Three sets of possible boundaries for the region
The idea of Central Asia as a distinct region of the world was introduced in 1843 by the geographer Alexander von Humboldt. The borders of Central Asia are subject to multiple definitions. Historically built political geography and geoculture are two significant parameters widely used in the scholarly literature about the definitions of the Central Asia.
The most limited definition was the official one of the Soviet Union, which defined Middle Asia as consisting solely of Uzbekistan, Turkmenistan, Tajikistan, and Kyrgyzstan, hence omitting Kazakhstan. This definition was also often used outside the USSR during this period.
However, the Russian culture has two distinct terms: Средняя Азия (Srednyaya Aziya or "Middle Asia", the narrower definition, which includes only those traditionally non-Slavic, Central Asian lands that were incorporated within those borders of historical Russia) and Центральная Азия (Tsentralnaya Aziya or "Central Asia", the wider definition, which includes Central Asian lands that have never been part of historical Russia).
Soon after the dissolution of the Soviet Union in 1991, the leaders of the four former Soviet Central Asian Republics met in Tashkent and declared that the definition of Central Asia should include Kazakhstan as well as the original four included by the Soviets. Since then, this has become the most common definition of Central Asia.
The UNESCO History of the Civilizations of Central Asia, published in 1992, defines the region as "Afghanistan, northeastern Iran, northern and central Pakistan, northern India, western China, Mongolia and the former Soviet Central Asian republics."
An alternative method is to define the region based on ethnicity, and in particular, areas populated by Eastern Turkic, Eastern Iranian, or Mongolian peoples. These areas include Xinjiang Uyghur Autonomous Region, the Turkic regions of southern Siberia, the five republics, and Afghan Turkestan. Afghanistan as a whole, the northern and western areas of Pakistan and the Kashmir Valley of India may also be included. The Tibetans and Ladakhi are also included. Insofar, most of the mentioned peoples are considered the "indigenous" peoples of the vast region. Central Asia is sometimes referred to as Turkestan.
There are several places that claim to be the geographic center of Asia, for example Kyzyl, the capital of Tuva in the Russian Federation, and a village 320 km (200 mi) north of Ürümqi, the capital of the Xinjiang region of China.