The aim of the article is to determine the legal foundations. The methodological basis of the study is analysis and synthesis, systems approach, genetic and comparative methods. Conclusions: The Byzantine law can be traced to the legislation of Basil I and Leo VI. However, jus gentium (law of nations) did not have sufficient representation in their codes. Therefore, the legal basis of Byzantine foreign policy consisted of customs and traditions that had been formed in diplomatic practice in ancient times.The system of international relations of Byzantium was hierarchical. The legal status of each participant in this system was determined by military power, political potential, tradition and religious identity. The relations between Byzantine and Kievan Rus’ can serve as a model of the application of international legal norms, which were based on the treaty of 944, which regulated the legal status of merchants, property rights, mutual military assistance and the use of territories on the coast of the Dnieper River estuary, Beloberezhye and the island of Saint Epherius (Berezan).

У статті досліджуються дискусійні питання стосовно обставин перших походів русів на Каспій (між 864-883, 909/910 і 910/911), відомих за свідченнями ібн Ісфандійара, Амулі та Мар’аши. Окрема увага приділяється місцю цих військових акцій у русько-хазарських відносинах, їх впливу на міжнародні відносини у регіоні навколо Каспійського моря. Автор розглядає шляхи, якими руси потрапляли до мусульманського світу, і пропонує власну версію маршруту руських контингентів. Відмічається зв’язок розглянутих походів з військовою акцією русів, що відбулась між 913 і 917 рр., відомою за описом аль-Масуді.

The debatable aspects of the eastern policy of Kyivan Rus during the reign of Prince Sviatoslav (964-972) are studied in the paper. Particular attention is paid to the campaigns of Rus troops against the Khazar Khaganate. The quantity of Sviatoslav’s eastern campaigns, the complement of their participants, the influence of Byzantine diplomacy on their organization, evidence of sources on the geography of military operations, and a role played by the Dnipro-Buh estuary as a strategic point on the Rus’ waterway to the Caspian Sea are considered. Analysis of written sources and the international context of the eastern policy of Prince Sviatoslav of Kyiv makes it possible to state that the military operations of Rus troops against Khazaria can be combined into two campaigns that are of 965 and 968-969. The route of those campaigns passed along the ancient waterway, which connected the Middle Dnipro region with the Caspian Sea. Waypoints of that route can be considered being the Dnipro trade route, the Black and Azov Seas, the Don and Volga rivers. An important place on this route was taken by the Dnipro-Buh estuary and its coast, in particular the island of St. Epheria (Berezan) and the Biloberezhzhia. It was there that Sviatoslav’s troops made a stop for rest and re-equipment of ships for seafaring. Probably, in 965, Sviatoslav’s allies were “a large group of Turks.” The latter could be recognized as a combined contingent of Oghuz and Pechenegs or detachments of one of those tribes. The campaign of 965 could enjoy the support of Byzantium, which during the 10th century considered Khazaria its competitor in the struggle for influence in the region.

The article is dedicated to the Rus' military campaign against Bardha'a, a major political center in Azerbaijan in the era of the Abbasid Caliphate. This was the military action of the Rus' in the Caspian region, which found the most complete consecration in the written sources of the East. In the context of political events, the arrival of Rus' in Azerbaijan should be at� tributed to August 944, and the departure from there at the turn of summerautumn 945. The likely participants of the campaign were contingents from the army of Prince Igor of Kyiv, who in 944 went on a campaign against Byzantium, which ended in peace negotiations. The campaign against Bardha'a took place with the support of Khazaria. Rus' arrived in Azerbaijan by ship, so their most likely route is: the Black Sea -the Kerch Strait -the Sea of Azov -the Don -portage to Sarkel -the Volga -the Caspian Seathe Kura. The version about the land route through the North Caucasus is not valid, and through the lands of the Byzantine vassals of Abkhazia, Kakheti, and Hereti is not confirmed by source information. The Rus' cam� paign against the Bardha'a became possible in the context of a serious crisis that the Caliphate was experiencing. One of the manifestations of the crisis was the growing popularity of opposition religious trends. Ismailism occu� pied a special place among such trends, including in the form of Qarmatian teaching. The Emir Marzuban, an opponent of the Rus in Bardha'a, consi� � dered himself as belonging to this teaching. Countering the Ismaili was one

No abstract