Regarding the history of the Turkish language, upon examining the works written in the Turkestan region between 1370-1465, it is seen that while some old elements belonging to the Karakhanid-Khorezm region continue in the written language, works penned during this time differ from Khorezm Turkish in terms of some linguistic features. Thus, an attempt to evaluate the formation processes of Chagatai Turkish, developments during the Timurid era, the effects of these developments on the Turkish language, as well as the language features that distinguish Chagatai Turkish from Khorezm Turkish will be made in this article. The determination of linguistic features differentiating the Khorezm and Chagatai regions in the works representing the first era of Chagatai Turkish will indicate how the transition from Khorezm to Chagatai Turkish took place in the written language.

Khorezm Turkish, Chagatai Turkish, middle Turkish.