Based on the study of open sources and published materials, the author made an attempt to explore a number of features of the organization of information and analytical work of the special services in the Donbass in the 1920s – 1930s. It is based on documents unknown to the scientific community, stored in archival institutions of Donbass, and various previously published materials by famous domestic researchers. The emphasis is placed on the fact that the Soviet leadership managed to rationally build, as a result of competent organization of a system of work with secret employees, the Cheka-GPU-NKVD bodies in the Donbass in the very first years of Soviet power established effective work to monitor the situation in the region. This made it possible to quickly take appropriate response measures in cases of threats to state security.

In the article, the author touches a number of issues related to the functioning of the occupation authorities in the Donbass during the Great Patriotic War. The article is based on unknown documents to the scientific community, stored in archival institutions of the Lugansk People's Republic, which are introduced into scientific circulation at the first time. The author emphasizes that the Nazi invaders formed a wide structure of the occupation authorities and administration. The author focuses on the fact that the main goal of the occupation policy of the enemy was the systematic destruction of the population and the robbery of the natural and material resources of Donbass.

The article covered the issue of transferring the Crimean region of the RSFSR to the Ukrainian SSR in 1954. The author emphasizes that the question of the reasons for the change by the Soviet leadership of the status and jurisdiction of the Crimean peninsula and the revision of the inter-republican borders is still far from its unambiguous decision. In 2014, the sixty-year period of Crimea and Sevastopol staying within the Ukrainian SSR was ended. The events under study in the 21st century are the subject of heated scientific discussions and pseudo-scientific speculations, and some political forces in Ukraine are actively discussing the issue of the political status of Crimea in their rhetoric. The article is based on documents from the funds of Russian and Ukrainian archives, and various published materials.

In the article, the author highlights some issues related to the reasons for Ukrainian collaboration, and peculiarities of the search and trial by Soviet state security agencies to war criminals and collaborationist elements during the Great Patriotic War. It was based on unknown documents to the scientific community, stored in the archival institutions of Donbass, and various previously published materials of famous domestic researchers. The author emphasizes that the work of the Soviet state security agencies to establish atrocities and search of war criminals and Nazi accomplices proceeded systematically and highly professionally. The result of their activities was a fairly significant number of war criminals and collaborators found and put on trial. This work strengthened the faith of Soviet citizens in the inevitability and justice of punishment for the crimes committed by the Nazis and their minions.

This article covers the issues of formatting the borders of Taurida in 1774–1917. The author sees it necessary to trace the prerequisites, causes, dynamics and principles of transformations of the status and boundaries of Taurida in the period under study. As a result of long-term Russian-Turkish conflicts, in the 18th century the region came under control and became an integral part of the Russian state. It is emphasized that the process of changes in the political status and administrative-territorial transformations took place against the background of the changing international situation that influenced its course, and setting various tasks in the field of public administration.

In this article the coverage of the status and formatting of the borders of Taurida was continued. The author sees it necessary to trace the prerequisites, causes, dynamics and principles of transformations of the status and boundaries of Taurida in the 1917–1921. It is emphasized that the process of changes in the political status and administrative-territorial transformations took place against the background of the changing international situation that influenced its course, and the setting by the state leadership of various internal political tasks. As a result of a long process of formatting, Taurida was divided between two Soviet states – the Ukrainian SSR and the RSFSR. Its borders are in this form in the 21st century.

Based on the analysis of little-known documents stored in domestic and foreign archival institutions and previously published materials, the article highlights the formation of the Russian-Ukrainian border on the Don in 1918. The author focuses on the features of lengthy and intense negotiations, sometimes accompanied by an escalation of interstate relations caused by the presence of mutual territorial claims. Following the talks, the states worked out a compromise option by concluding an agreement on the mutual recognition of sovereignty and the establishment of state borders of the Don and the Ukrainian State. However, implementation of the signed agreements was hindered by foreign policy events and the subsequent change in the domestic political situation in the context of the growing chaos of the Civil War. The end of the First World War and the subsequent withdrawal of the troops of the Central Powers brought down the pro-German government of P.Skoropadsky, and in the Don defeated military-political circles began to oriented toward the Entente countries.

The article covers the issues of a key stage in the construction of the Russian-Ukrainian inter-republican border in the 1920s. The author grounded on the documents and modern publications of leading historian scholars stored in domestic and foreign archival institutions. The author emphasizes that inter-republican delimitation in the 1920s had opposite vectors - from the application of an ethnographic criterion to the involvement of economic and political arguments. The result of the confrontation was the adoption of the option of delimitation agreed upon by the parties, drawn up by the corresponding Decree of the CEC of the USSR.

In the article, the author coverage of the main issues related to the final formatting of the Russian-Ukrainian inter-republican border in the 1926–1928s. It is emphasized that the dynamics and content of the Russian-Ukrainian demarcation in the 1920s. identified a whole range of domestic political reasons. The parties again turned to ethnographic criteria, reinforcing them economic and political arguments. The result of the territorial disputes was the clarification of the inter-republican borders in October 1928. These boundaries served as the basis for the establishment of the land state border between the Russian Federation and Ukraine in 1991.

The article covers the issues of the initial stage of the formation of the Russian-Ukrainian border in the 1917–1919s. It is based on the study of the archive documents, contemporary publications of leading experts. The prevailing in the border areas with mixed population structure complicated the borders along ethnic lines. The territorial dispute was suspended in 1919 with Ukraine signing the Treaty on Borders with the Russian Socialist Soviet Republic, where the parties confirmed the expediency of the pre-revolutionary provincial administrative-territorial differentiation.

The article covers the complex transformation issues of the Russian-Ukrainian border in 1920. It is based on the study of the archive documents, critical analysis of publications of leading historians. The author marks, that economic factor determine the creation of the Donetsk province and the transfer to it the some Russian ethnic territories, that caused intense disputes about the contours of the Russian-Ukrainian border. The administrative-territorial dispute was settled by the orders of the Center, but the decision did not satisfy the parties.