Based on the materials of the Russian State Archive of Ancient Acts (RSAAA), questions of the ethnic composition of the main city of Siberia - Tobolsk in the XVII century are examined. Attention is paid to the characteristics of various groups of the urban Turkic population. A review of census books on Siberia of the 17th century is completed. Particular attention is paid to the analysis of the “Census book of Tatar yurts in river Irtysh”, introduced by the authors into scientific circulation. The results of a comparative analysis of data from the census book of 1682 with other sources are presented. The question is raised about the features of the population formation of the Tatar settlement of Tobolsk. It is proved that the formation of the Tatar urban population included various categories of the Turkic population. A classification and characterization of such population groups of the city of Tobolsk as service Tatars, feudally dependent Tatars, and Bokharans are proposed. The novelty of the study is determined primarily by the lack of knowledge of the ethnic composition of Siberian cities, in particular, in the 17th century. The relevance of the study is due to the need to identify ways of forming the population of the Siberian capital.