Аннотация:The chapter analyses the interaction of modern Tajik and its dialects with a group of so-called Pamir languages in the Mountainous Badakhshan Autonomous Region of Tajikistan, where the population speaks various Iranian vernaculars of Eastern and Western Iranian origin. In the early medieval period this area was strongly influenced by the Persian language - the language of administration, culture and science. Tajik is closely related to Persian; it evolved along with modern Persian and Afghan Dari through the shared cultural background and language of the classical literature of the 10th-15th centuries. During the second millennium, the Persian-Tajik language attained a high status throughout Central Asia, and by the early 20th century, it became the official state language of the Republic of Tajikistan. In modern Tajikistan the Western Iranian Tajik language - the state language - is present in written and oral forms; various heritage Eastern Iranian languages, the Yaghnobi language as well as the group of Pamir languages are spoken there, none of which has a written tradition. This study provides an overview of the sociolinguistic situation in the Mountainous Badakhshan Autonomous Region. It discusses the areal stratification of the continuum of Tajik dialects and the interaction of these dialects with the group of Pamir languages, in particular Shughnani. The research further highlights issues arising from these contacts, in particular concerning vocabulary and word formation.