The article is devoted to comparative research of blade consonants in the language of Kalmyk Derbets and Derbets of Mongolia since these Derbets used to represent a unifi ed people as a part of Djungar Khanate on the territory of Central Asia. The article set an objective of identifying common Oirat features representing Protomongol language as well as specifying characteristics unique for the Derbets of Kalmykia and Mongolia. The results of the research revealed certain similarities in the blade consonant sounds between Kalmyk and Mongol Derbets which are traced back centuries ago. Specifi c feature of the Mongol Derbet language is the presence of affricate dz along with a fricative z that appeared under Khalka influence.