The paper is the first attempt to obtain insights into the legal relations of the Russian Empire with the countries of Central Asia based on the concept of frontier modernization. The author identifies the main stages of legal cooperation between Russia and Central Asian states in the 18th — early 20th centuries, reveals the main means and methods, by which the Russian government tried to influence the legal development of the countries and peoples of the region in each of the investigated stages. Here, he compares them with similar processes implemented by the Russian Empire in its other eastern border regions. According to the author, the incomplete frontier modernization process in the Central Asian khanates (unlike in Transcaucasia, Kazakhstan, etc.) was associated both with their formal legal status (the actual protectorate of the Russian Empire with formal independence) and with the political situation (the revolutionary events of 1917, which toppled the empire).