History: Central Asia, 140 Years Ago

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. This definition was also often used outside the USSR during this period.
However, the Russian culture has two distinct terms: Средняя Азия (Srednjaja Azija 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 (Central'naja Azija or "Central Asia", the wider definition, which includes Central Asian lands that have never been part of historical Russia).
Soon after independence, 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 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, Tibet, northeast Iran (Golestan, North Khorasan and Razavi provinces), Afghanistan, Northern Areas, N.W.F.P., Azad Kashmir and Punjab provinces of Pakistan, Punjab, Kashmir and Ladakh of India, central-east Russia south of the Taiga, and the former Central Asian Soviet republics (the five "Stans" of the former Soviet Union).