Not only it has long been argued that the the language which today commonly known to us as Middle persian is not a direct ancestor of Modern Persian (Dari/Farsi/Tajiki), but even the very claim that Middle Persian itself is a continuation of another earlier Iranian language, [nowadays commonly] known as Old Persian, has been challenged. (for example by the renown Iranologist Windfuhr)
By Old Persian (OP) it is usually meant the language in which Achaemenid era inscriptions such as that of Behistun in Southeastern Kurdistan and Van Castle in Northern Kurdistan have been recorded.
But there are serious linguistic, historic and even georaphic problems challenging this politically motivated propaganda introduced by the 19th century British soldiers and generals, disguised under the name of scholars and historians, sent to Middle East.
Historically to the both Babylonians and the Greeks, the early Achaemenids (i.e. the first century of the empire), during whom the insceiptions in question have been written, is referred to as Medians.
Not only this, even the founders of the inscriptions considered themselves as Median. To make this clear, We analyse the phrase, in which Darius the Great says he is from Parsa (a non ethnic name, meaning from ''borderland'' in Old Iranic languages) of ''Aryan'' origin. Arya which reflects his ethnic background, was endonym of the Medes (otherwise known under the name of Uman Manda or Guti by Semitic Mesopotamian lowlanders). Herodotus clearly explains that the Medes real name was Aryans, while the Persians endonym was Artaeans and that was also how they were known by other peoples.
Linguistically, as mentioned above, modern and even middle Perian have little in common with the language of Achaemenid inscriptions, if compared with modern northwestern languages such as Kurdish and Balochi which stand far closer to it, both phonetically and in syntax. The renown Iranologist mackenzie after a deep study of Kurdish language, concludes that it has significant resemblances with [the language he knew as] Old Persian (the true Median). He goes as far as to say the Kurdish syntax rarely goes beyond that of Old Persian.
Consequently one can presume that there is a widespread misunderstanding regarding the language of Medians, and that of the Scythians. What many modern scholars assume to be Median seems to be none than the ancient Scythian language. The true Median language is already preserved throughout western Iran, the Greater Kurdistan.
