http://www.iranicaonline.org/articles/turkic-loanwords"TURKIC LOANWORDS IN PERSIAN
Turkic-Iranian language contacts, as well as reciprocal loaning/borrowing of words, go back to the era of the Old Turkic language. During that period, the Turkic languages mostly borrowed from the Iranian languages of Central Asia (e. g., Sogdian, Middle Persian, or Saka). In this regard, the Uighurs borrowed especially the basic vocabularies of religious spheres of Manicheism and Buddhism (e. g., Uig. ažun ‘world’ < Sogd. ʾʾžwn; Uig. tamu ‘hell’ < Sogd. tmw, etc.). An effective reverse influence can be observed as well, except for some borrowed Turkic names (e. g., in the Middle-Pers. Maḥrnāmag [the title of a Manichean hymn book]) from the beginning of the penetration of turcophone groups into the Persian language area to the time of the conquests of Čengiz Khan (d. 1227) and his successors. Of the Iranian languages, Persian and Tajik, which are to be seen separately from each other in this regard, were especially affected by these influences."