The Iranian Languages constitute one of the major language families in the world. There are currently more than twenty distinct living languages and perhaps hundreds of dialects that are believed to belong to this language family. At least, two hundred million individuals speak one of these languages as a mother tongue and the total number of speakers of add up to even more than that, with some persons being fluent in more than one Iranian Language. The Iranian Language family is also one of the oldest attested language groups we know today and there is a plethora of ancient texts and inscriptions that give us a detailed picture how these languages developed over thousands of years. The importance of Iranian Languages is therefore immense for understanding many aspects of linguistic change including grammaticalization. People with any level of interest in linguistics should become familiar with Iranian Languages and should at least know where they came from and what languages they include.
As you might have guessed Iranian Languages take the name from a geographical location that is Iran. All Iranian languages are spoken either in Iran or in neighboring countries and starting with the earliest attested examples of Iranian Languages, this language group has more or less been the major language of daily communication in this land. The most famous Iranian Language is, of course, the Persian Language. Persian is the official language in Iran. It is called Dari in Afghanistan and Tajik in Tajikistan, though there is no big difference between these three. Altogether a native speaker population of close to 150 million is estimated, which makes Persian by far the largest extant Iranian Language. Persian is also one of the richest languages in the world. Persian poetry is famous with hundreds of unique poets that composed poems in classical verse throughout the medieval centuries. People of Iran are known for their love of the language, which they see as the most important element of their heritage. Persian, also known as Farsi, is a direct descendant of the Middle Persian and Old Persian languages, which are the two historical Iranian languages that we know best.
Another major Iranian Language is the Pashto. This language is spoken in Afghanistan and at first sight, it is quite different form the regular Persian. The speakers of the languages could never understand each other without an interpreter. However, in the eyes of a linguist, they hve much in common including countless cognate words. While Persian mostly has prepositions that tell us where or when something is taking place, Pashto has a large inventory of prepositions, postpositions and circumpositions. Since we can trace the origin of most of these adpositions to nouns, a comparative study of Persian, Pashto and other Iranian Languages can reveal mush about how languages change. Indeed, the adpositions derived from nouns in Iranian Languages is something that linguists should not be missing.