The Indo-Iranian languages are traditionally spoken in West, Central, and South Asia. The area in which Indo-Iranian languages were originally spoken was much larger than at present; in fact, they were previously spoken as far west as Eastern Europe.
Indo-Iranian languages are usually divided into two branches: Iranian, and Indo-Aryan (a.k.a. Indic to avoid the term "Aryan" though, to some, Indic connotes a more restricted geographic region). The Iranian languages are primarily spoken in West and Central Asia, and the Indo-Aryan languages are spoken in South Asia. However, this division is somewhat controversial: arguments have been made for two additional branches of the Indo-Iranian family, Dardic and Nuristani (discussed later), which traditionally have been classified under Indo-Aryan (Indic) if they are discussed at all.
Thus, while parts of this website and other sources may refer to the "Indic" family as [loosely] including the Dardic and Nuristani groups, the Indo-Iranian family will be described here as having four branches: Iranian, Indo-Aryan, Dardic, and Nuristani. "Indo-Aryan" as used on this page refers to Indo-Iranian languages that are not Iranian, Dardic, or Nuristani. Among the oldest-known Indo-Iranian languages are Sanskrit (an Indo-Aryan language) and Avestan (an Iranian language); these two are among Indo-European languages having the most ancient written texts.
The Iranian languages comprise essentially four subdivisions: Northeastern, Southeastern, Northwestern, and Southwestern. Most of the Northeastern Iranian languages are extinct, e.g. Avestan, with the notable exceptions of Ossetian (spoken in the Caucasus region, e.g. in Georgia, southern Russia, and Turkey) and Yaghnobi (spoken in Tajikistan). Southeastern Iranian languages are spoken in Afghanistan, Tajikistan, Pakistan, and what is now northwestern China.
Northwestern Iranian languages include Kurdish and other unofficial languages spoken in Turkey, the Middle East, and parts of Pakistan. An example of a Southwestern Iranian language is Pashto, one of the two official languages of Afghanistan; others include Persian (evolved from Old and Middle Persian) and a few languages closely related to it, such as Dari.
Avestan and Old Persian are the oldest documented Iranian languages, and lessons for both are available from the LRC; see Old Iranian Online.
The oldest-known Indo-Aryan languages are Sanskrit, Prakrit, Pali, and Apabhramsa. Classical Sanskrit was used as a literary language in South Asia. "Prakrit" is a term used to refer to the ancient vernacular Indo-Aryan languages spoken there, upon which more modern Sanskrit seems to have been based. Pali is another ancient Indic language, similar to Prakrit but used primarily in writing Buddhist texts. Lessons for Ancient Sanskrit, which was extinct before the Classical period, are available from the LRC; see Ancient Sanskrit Online.
Apabhramsa is the ultimate forerunner of most modern Indo-Aryan languages. Several vernacular languages were derived from it, and those languages evolved into the modern Indo-Aryan languages. For example Sauraseni, one descendant of Apabhramsa, is the ancestor of many Western Indo-Aryan languages such as Gujarati and Rajasthani.
Modern Indo-Aryan languages are classified according to the geographical regions in which they are spoken. For example, two very widely spoken languages, Hindi and Romani, were originally spoken in Central India; thus they belong to the Central Zone. Bengali, an even more widely spoken Indo-Aryan language, is spoken in eastern India and Bangladesh, so it is classified as an "Eastern Zone" language.
Dardic languages are spoken in the northernmost parts of India, Pakistan, and Afghanistan. No Dardic languages are well-studied, though some are better known than others. Relatively more information is available for two of these languages in particular, Kashmiri and Shina. Kashmiri is probably better known because it has an unusually long literary tradition. According to Grierson, however, the most basic words in Kashmiri are of Shina origin; this may help to explain why Shina is also better known.
The areas in which the Dardic languages other than Kashmiri and Shina are spoken are rather remote; this is also true of Nuristani languages (see below), which overlap in these areas. Dardic and Nuristani languages also retain some features from Sanskrit that are not preserved in more modern Indo-Aryan languages; for example the sound "tr" is often converted to "t" in Indo-Aryan languages, but the original "tr" remains in many Dardic and Nuristani languages.
Nuristani languages -- sometimes known also as "Kafir" languages though Nuristani seems to be the more widely accepted term nowadays -- are spoken in the northernmost parts of Pakistan and Afghanistan. They are little-studied because they are spoken in remote regions that are politically unstable, and they have no long-standing literary tradition. In these respects they are quite similar to most Dardic languages. Indeed, sources tend to be inconsistent about the status of these languages, differing in their classifications as to which are Dardic vs. Nuristani. Recent sources tend to list five Nuristani languages (albeit by various names, depending on the source): Prasuni, Bashgali, Ashkunu, Tregami, and Waigali.
Both the Dardic and Nuristani language groups were originally classified as "Indo-Aryan" languages, but languages in these groups are so different from the Indo-Aryan languages that some claim Dardic and Nuristani to be separate families. The differences between Dardic and Nuristani are not always clear. Nevertheless, it is considered good practice to distinguish Dardic from Nuristani, and we try to observe the distinction.