Central Asia is the core region of the Asian continent and stretches from the Caspian Sea in the west to China in the east and from Afghanistan in the south to Russia in the north. It is also sometimes referred to as Middle Asia, and, colloquially, "the 'stans" (as the five countries generally considered to be within the region all have names ending with that suffix) and is within the scope of the wider Eurasian continent.
In modern contexts, all definitions of Central Asia include these five republics of the former Soviet Union: Kazakhstan (pop. 16.6 million), Kyrgyzstan (5.5 million), Tajikistan (7.6 million), Turkmenistan (5.1 million), and Uzbekistan (29.5 million), for a total population of 64.7 million as of 2012. Other areas included are Afghanistan, Pakistan, Mongolia, and sometimes Xinjiang and Tibet in western China and southern Siberia in eastern Russia.
Various definitions of its exact composition exist, and no one definition is universally accepted. Despite this uncertainty in defining borders, it does have some important overall characteristics. For one, Central Asia has historically been closely tied to its nomadic peoples and the Silk Road. As a result, it has acted as a crossroads for the movement of people, goods, and ideas between Europe, West Asia, South Asia, and East Asia.
The Kyrgyz (also spelled Kirgiz, Kirghiz) are a Turkic people living primarily in Kyrgyzstan.
There are several etymological theories on the ethnonym "Kyrgyz."
The word "Kyrgyz" is derived from the Turkic word "forty", with -Iz being an old plural suffix, referring to a collection of forty tribes.
Tajik (Persian: تاجيک, Tājīk; Tajik: Тоҷик) is a general designation for a wide range of Persian-speaking people of Iranic origin, with traditional homelands in present-day Afghanistan, Tajikistan, and Uzbekistan. There are also smaller communities living in Iran and Pakistan; consisting mainly of refugees from Afghanistan and immigrants from Tajikistan.
In terms of language, culture, and history the Tajiks are closely related to the Persians of Iran.
As a self-designation, the term Tajik, which earlier on had been more or less pejorative, has become acceptable only during the last several decades, particularly as a result of Soviet administration in Central Asia. Alternative names for the Tajiks are Fārsī (Persian), Fārsīwān (Persian-speaker), and Dīhgān (cf. Tajik: Деҳқон, Dehqon, literally "farmer or settled villager", in a wider sense "settled" in contrast to "nomadic").
The Tajiks of China, although known by the name Tajik, speak Eastern Iranian languages and are distinct from Persian Tajiks.