Central Asia is largely coextensive with Turkestan. In modern context, Central Asia consists of the five former Soviet republics of Kazakhstan, Kyrgyzstan, Tajikistan, Turkmenistan, and Uzbekistan. The nations of Afghanistan and Mongolia may also be included in Central Asia, in addition to the western Chinese provinces of Inner Mongolia, Xinjiang, Qinghai and Tibet.

Definitions

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. Many text books still refer to this area as Turkestan, which was the name used prior to Stalin's rule.

The most limited definition was the official one of the Soviet Union that defined the "Middle Asia" as consisting solely of Uzbekistan, Turkmenistan, Tajikistan, and Kyrgyzstan, but did not include Kazakhstan and Mongolia. This definition was also often used outside the USSR in this period. However, the Russian language has two distinct terms: ??????? ???? (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 ??????????? ???? (Tsentral'naya Azia or "Central Asia", the wider definition which includes "Central Asian" lands that have never been part of historical Russia). However, there lacks a meaningful distinction between the two in the English language; and so "Central Asia" is used for both Russian usages, thus creating some confusion.

Soon after independence, the leaders of the five 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 general history of Central Asia, written just before the collapse of the USSR, defines the region based on climate and uses far larger borders. According to it, Central Asia includes Mongolia, Western China (including Tibet), northern India (Himachal Pradesh, Jammu & Kashmir, and Punjab states), northeast Iran (Golestan, North Khorasan, and Razavi provinces), Afghanistan, northern Pakistan (Punjab, Northern Areas, and N.W.F.P. provinces), central-east Russia south of the Taiga, and the former Central Asian Soviet Republics (the five "Stans" of the former Soviet Union). 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, the Turkic/Muslim regions of southern Siberia, the five republics, and Afghan Turkestan, northern Pakistan and Afghans. The Tibetans are also included. Insofar, the mentioned peoples are considered the "indigenous" peoples of the vast region.