The first materials under the name of Khalaj Turkish were compiled and published by the Eastern linguist Minorsky in 1940. The second compilation of Khalaj belongs to Mohammad Mogaddam, who performed field studies in the areas of Tafraş and Aştiyan and compiled four different dialects of the Turkic language of Khalaj spoken there.

However, Doerfer was the first to determine the importance of Khalaj. Based on the deficiencies in previous studies, Doerfer considered conducting field studies in the region to be necessary. He sent his students to Iran in 1968 to identify the villages where Khalaj was spoken and to compile materials in order to verify Moghaddam’s materials. Mogaddam’s materials were given to volunteers in Persian in three different areas, and they were asked about the words’ equivalency in Khalaj.

The collected materials were examined in Doerfer’s (1971) book Khalaj Materials in 1971. The book’s third chapter contains materials from the dialects of Talxab, Mansurabad, and Xaltabad that are given in word lists. The longest most comprehensive list contains 319 words compiled from the Talxab village. The word lists from Mansurabad and Xaltabad have 111 words in common with the Talxab list.

Afterward, a second fieldwork study was conducted in the Khalaj region in 1969. Doerfer personally participated in this study. Thus, a comprehensive study of the Khalaj was carried out during this period, and the published studies are still currently the source on Khalaj.

The first and only Khalaj dictionary was conducted in these field studies. The Wörterbuch des Chaladsch dictionary contains Talxab dialectal words that Doerfer and Tezcan published in 1980. The second critical study based on these materials is Lexik und Sprachgeographie des Chaladsch and contains two volumes. The words are arranged thematically, and each word’s Khalaj meaning is given alongside their German headwords.

The issues that increase the importance of this book are how it shows the dialectal differences between words and how it provides etymological information about the words. Doerfer’s (1988) Grammatik des Chaladsch discusses the phonology and morphology of Khalaj. Also, Tezcan and Doerfer’s (1994) Folklore Texte der Chaladsch, provides text samples of Khalaj. The samples are sorted into four chapters. Chapter 1 provides samples from the first field study, Chapter 2 provides samples from the second field study, and Chapters 3 and 4 address the field samples obtained by Müseyyeb Arabgol. Based on these studies, quite a volume of scientific research was carried out on Khalaj.

The importance of Khalaj was realized through the work of Doerfer and his team, thanks to which they identified the archaic phonetic features and vocabulary of Khalaj and put forth new classifications on the Turkic language. Khalaj is positioned as an independent branch in the classification of Turkic languages due to it having the linguistic features of Old Turkic.

This study is presented in order to determine the changes that have occurred to words in Khalaj as published by Doerfer (1968). Therefore, the words in the fifth chapter of Khalaj Materials were given to the people native to the three areas. The words were given in Persian, and the people were asked for the Khalaj equivalents. The similarities and differences were revealed by comparing the words compiled from the Xarrab (now known as Baharistan) region in January 2022 with those compiled by the Doerfer team in 1968. The article then determined how much the Khalaj vocabulary had changed under the influence of other languages over the past half a century. According to the studies, there was a 15%-word difference in Khalaj Turkish this half-century. Today, Persian words are used about 7% more frequently than Khalaj words. Meanwhile, only two words Doerfer had recorded as Persian in his compilations were found to be recorded as Khalaj in this study.

The facts that the Khalaj people have been in Persian neighborhoods, that Persian is the official language of the country, and Persian being used as a prestigious language among newer generations has led to Khalaj being used less over time. In addition, while comparing the two reviews, approximately 8% of different Turkish-origin words are seen to have been used . The differences between the Khalaj dialects and the acceptance and giving of words from other Turkish languages such as Azerbaijan Turkish could have led to this. In addition, different words have been determined to be used for concepts in the language, and this can lead to the detection of different words in the same language while both are actively used in conversations.