Persian language is mostly a prepositional language, which means most of it adpositions come before the nouns. There are indeed several prepositions in Persian at different stages of grammaticalization and they are responsible for almost every semantic job in the sentence, including cases, spatiotemporal relations and all other relations. However, there is also one postposition, which more than deserves a mention as it is per se the most commonly used adposition in the entire language, doing a very unique job. This postposition is RA (را) and it marks the definite direct object and has been doing that job, at least, for the last few centuries. When the New Persian language first emerged more than a thousand years ago, RA was somewhere between an accusative marker and a dative marker that also seems to have had some other weird and ambiguous functions. In any case, RA is a very interesting word or a morpheme as linguists like to call it and I think I will now go on to tell you what sort of grammaticalizaion it went through to become what it, now, is.
There is consensus among linguists as to where this RA particle came from. Its Old Persian ancestor is RADIY, a noun only attested in locative case. We do not know the nominative of this Old Persian noun, nor do we know what exactly it meant but taking a look at its apparent Indo-European cognates we can estimate its meaning to be somewhere around “blessing” or “satisfying” or “preparation”. Whatever the noun itself meant, we know that its locative case “radiy” meant “for the sake of”. It became the postposition RAD in middle Persian and it already had a dative function. A few centuries late we see it again, this time as RA in Early New Persian, signifying the dative inaddition to accusative and some form of genitive. This is a classic case of grammaticalization in Persian.
Persian and other Iranian Languages, contain so many examples of grammaticalization of adpositions but we do not have the time and space to review every one of them, here. And yet, I will write about another classic case of grammaticalization throughout the Iranian Language family that has been going on since the dawn of the Indo-European Languages. Now, take a look at the ENTER button on your keyboard. You know what it means: To get into something. You would be surprised to hear that its exact sound-for-sound cognate exists in Persian. ANDAR in classical New Persian texts means “inside, in, at”. Essentially, it is the locative case marker and even today, Persians know what it means because they love the classical poetry. ANDAR has developed out of the Indo-European word ANTARA, that has cognates in virtually every Indo-European language. In Persian, it went through a sort of adverbial stage and then it went into further grammaticalization to become an adposition. In the earliest specimens of New Persian, it is seen both as a preposition and a postposition. Yet, it didn’t take more a few centuries for ANDAR to be fixed as a preposition and more interestingly, sometime around the middle of 11th century, it became DAR. We do not know the reason for this quick phonetical trimming that occured but what we know is DAR is one of the key adpositions in Persian, today.
These and other examples of Persian adpositions provide interesting material for grammaticalization studies.