Farsi (or Persian) is part of the Indo-Iranian group of the vast Indo-European (or Indo-Aryan) family of languages. Two main subgroups constitute the Indo-Iranian group of languages: the Iranian and the Indian subgroup of languages. All the languages originally current on the vast Iranian plateau, stretching from the Pamir region in the east to the borders of present-day Iran in the west, form the Iranian subgroup of languages. These languages were spoken by the Aryan tribes, who approximately from the second millennium B.C. started their migration onto this plateau.

The Iranian languages are divided into three groups: the Old languages (which include Avestan, Old Persian and Median), the Middle languages (which include Parthian, Pahlavi, Soghdian, Kharazmian and Khotanese) and the Modern languages (which include Persian or Farsi and many different dialects). The Persian language carries an old cultural and literary tradition, and it once carried great significance for neighbouring peoples, the Turks in particular. Old Persian was the language of the Achaemenid Empire (6th–4th centuries B.C.), while Middle Persian was that of the Sassanians (3rd–7th centuries A.D.). Modern Persian, in its present form, developed after the Muslim conquest of Iran, during the 10th century (Thackston, 1993: xi; Lambton, 1953: ix), and in certain lands it has even become the language of politics and cultural accomplishments (Alam, 1998: 317–349; Cohn, 1985: 284–295).

Iran was divided into many linguistic regions, the main languages being Pahlavi, Dari, Farsi, Khuzi and Suryani (Syriac) (Al-Nadim, 1991: 19). In addition, a large number of dialects existed in Iran as well, differentiated from each other by region (province, town, etc.) (Khanlari, 1972: 81–85). Farsi is the developed, but simpler and more regular, form of Dari. Its forms are both shorter and more economical, with multisyllable and multiflexion words giving way to easily grouped words of few syllables.