Khalaj language
Khalaj, also known as Arghu, is a divergent Turkic language spoken in Iran and Azerbaijan.
Ethnologue and ISO list an Iranian language "Khalaj" with the same population, but Glottolog lists it as spurious. The International Encyclopedia of Linguistics, Volume 3 by Williamm J. Frawley lists it as an Iranian language as well, and mentions furthermore that, apart from being spoken in both Iran and Azerbaijan, that it is related to Kurdish and Talysh.
Classification
Khalaj has traditionally been classified with Azerbaijani dialects, primarily because of its proximity to them. However, it is not a dialect of Azerbaijani, as previously supposed. Further, features such as preservation of three vowel lengths, preservation of word-initial Proto-Turkic *h, and lack of the sound change *d → y has led to a non-Oghuz classification of Khalaj. An example of these archaisms is present in the word hadaq ("foot"), which has preserved the initial *h and medial *d. The equivalent form in nearby Oghuz dialects is ayaq. Therefore, it is an independent language that became distinct very early from other extant Turkic languages. Because of the preservation of these archaic features, some scholars have speculated that the Khalaj are the descendants of the Arghu Turks.