The process of formation of Tajik nationality started as early as the 4th – 5th century and ended on the verge of the 9th – 10th centuries with the Samanids state. The ethnic groups of Tajiks were some of the ancient tribes of Central Asia: Bactrians, Sarmatian, Tokhars, Soghdians, Saks, and Massagets. As all the Iranian-speaking people, and also Dards of India and people of Nuristan, Tajiks consider their ethnic origin as Arians. The direct predecessors of Tajiks were people speaking Eastern-Iranian languages. However the predecessors of modern Tajiks did not speak Persian — as they were related to the Western Iranian group of languages. The new Persian language, known as “farsi” in Iran and Dari language in Afghanistan is defined as “Tajik language” in Central Asia starting from the 8th century AD. The Eastern-Iranians adopted the Persian language in the period of the Muslim invasion of Central Asia by Arabs, which provoked migration of Persians (western Iranians) to Central Asia (including western China). As a result of this influence, local Eastern Iranians (Tajiks) started to speak Persian. But, undoubtedly backgrounds for their languages were the early Eastern Iranian languages and dialects.

Anthropologically Tajiks are referred to as a Caucasian race. Dark hair and eyes, skin tones range from olive-skinned to light skin color which are typical for Tajiks. Inhabitants of the valley areas of Soghd have noticeable Mongoloid features: less hair, wide faces and narrow-shaped eyes. Lighter colored hair and eyes are common in the Pamirs.

The national composition of the country is defined by its historical fortune. The country until the great geographical discoveries was on the world trade roads and for the entire period of existence it repeatedly underwent different invasions and conquests. The territory of Tajikistan, offered spacious areas and therefore stimulated an unusual diversity of the ethnic composition of the population especially in the Southern areas.

From the general mass of Tajiks, the pre-Pamirian Tajiks single out by their languages, life style and other signs. These are Shugnani-Rushani, Khufi, Yazgulyami, Vakhani, Ishkashimi, and Bartangi. They form the Gorno Badakhshan Autonomous Oblast (GBAO) within Tajikistan. Another special group of Tajiks are the Yaghnobi – direct descendants of Soghdians, living in the high mountain valley of Yaghnob (influx of Zerafshan). Their language is one of the dialects of ancient Soghd languages, which was spoken by a part of modern Tajiks ancestries until invasions of Central Asia by Arabs in the 7th and 8th centuries. Now Yaghnobis speak two languages – Yaghnobi and Tajik.

For Tajikistan, as for any mountain region, the uneven distribution of population on high altitude areas is typical. The lower areas of the large river valleys are intensively developed and densely populated. Slopes and highlands are less populated or are devoid of any permanent inhabitants. The main mass of the population live in cities, districts and villages, located at altitudes up to 1,000 m. The majority of Tajikistan’s population live in zones from 1,000 to 2,000m and only some at the altitude of more than 2,000m.

In the South of Tajikistan a small number of Arabs live. Turkmens of the Ersari tribe settled in the lower reaches of Vakhsh from the middle of 14th century. Kyrgyz people settled in the North-Eastern part and Eastern Pamirs. Central Asian gypsies live in separate clans – local people call them “jugi” or “luli”. Russians, Tartars, Georgians, Armenians, Germans and Central Asian Jews also live in the cities of Tajikistan.

The majority of the Tajik population professes Islam. Most of the country’s population are Sunni-Muslims, and only a small proportion of Tajiks are Shia Muslims. One of the characteristics of Tajikistan is its high population growth with now about 9 million people living in the country.