The article comes to view the development of Kryashens, which are connected with Udmurts or with the territory of the modern Udmurt Republic, in the last third of the 18th - middle 19th century. The area in question is the Malmyzh and Elabuga counties of Vyaka province and Mamadysh county of Kazan province. The “Udmurt old-christened” ethno-class status of the inhabitants of the settlements of the Srednekushket volost’ of the Malmyzh county, noted by the sources, was to some extent a “tribute to tradition”. In Mamadysh county in 1834 historically associated with the Udmurts Kryashen settlements were located in 3 volosts; the tendency for their assimilation, which was reflected in the middle of the 18th century, was completed here even earlier, in the first third of the 19th century. In Yelabuga county since its formation there was a old-christened small administrative-territorial unit. In the historical settlements of Kryashens, located in our days in the territory of the Udmurt Republic (Grakhov and Kizner districts), their Udmurt origin, with few exceptions, is not traced. The appearance of this sub-ethnic group of Tatars here was mainly due to migration processes from the nearest southern territory. In this period the norm for the Kryashens was shared with other peoples - Tatars, Mari, Udmurts, and later - Russians. The presence of Russians in historical Kryashen villages steadily increased over time. From the late 18th century the Kryashen volosts often included villages with different ethnic-caste identity. From the second quarter of the 19th century the disappearance of the Kryashen small administrative-territorial units began. It was caused, first of all, by transformations of the state in this sphere.