In the article the attention to such important theoretical problem as definition of the historical region is paid. This question is not so simple as it seems to be. The historian of Russia deals with borders which were constantly changing. This remark is correct in relation to administrative, economic, ethnic boundaries. Besides that, unlike France, Italy and other European countries we cannot observe in Russia historic areas, such as Tuscany or Burgundy. The problem of definition of the historical region has two aspects - theoretical and practical. At the theoretical level it is necessary to define what historical region should be studied and why exactly this one. So, it is the best of all, for instance, to study genesis of feudalism in Europe in France because French feudalism is typical. The practical aspect of the problem boiled down to definition of the concrete borders of the historical region. That is why it is necessary to make theoretical justification of borders of the historical region under research, but not just using of administrative borders of provinces and uyezds (counties). To achieve this scientific purpose the following research tasks was set: to define criteria of allocation of the historical region, to analyze features of allocation of territorial borders in relation to the Russian history, to establish, relying on theoretical criteria a possibility of definition of historical regions in Western Siberia. As an example, we offered allocations of such historically developed region as Zauralye or Trans-Ural region which is situated on junction of the Urals and Siberia and therefore often does not get to the field of a research of the Ural or Siberian historical research. The methodology of this article relies on the principle of historical-geographical zoning. The problem field of the article is defined proceeding from the analysis of the monographic and dissertation research devoted to history of Western Siberia. Often in the titles of historical researches there is the Tobolsk province or Western Siberia while it is only about some uyezds (counties). When it is dictated by an object of research (administration, taxes, court) such approach is quite appropriate, but in such cases as trade, history of everyday life, culture, etc. we consider this approach unproductive. As a result, authors come to a conclusion that it is needed to be done a complex approach to allocation of the historical region. It assumes several parameters: administrative-territorial division, ethnic and geographical factor. Besides, it is necessary to consider type of economic activity. So, to the north of the Tobolsk county the appropriating economy prevailed, while to the South agriculture has been extremely developed, and in the southeast - nomadic cattle breeding prevailed. We shall try to apply the principles marked above when determining the concrete historical region, namely the Zauralye or Trans-Ural region. This term begins to be used steadily from the first half of the 19th century and originally designated east agricultural counties of the Perm province. However, it was not widely adopted. In the second half of the 20th century Trans-Ural region has been "appropriated" by the Kurgan region, but finally this term began to be associated with this area from 1990th. Summing up the results, it is possible to note that this article contains rather an invitation to a discussion and search of the answer to such questions, as what and how should be studied within the framework of local history.