The Rus'–Byzantine Treaty between the Byzantine emperor Constantine VII and Igor I of Kiev was concluded either in 944 or 945 as a result of a naval expedition undertaken by Kievan Rus against Constantinople in the early 940s. Its provisions were less advantageous for the Rus than those of the previous treaty, associated with the name of Igor's predecessor Oleg. It was one of the earliest written sources of Old Russian Law.
The text of the treaty, as preserved in the Primary Chronicle, contains a list of the Rus' plenipotentiaries (no fewer than fifty are named). The overwhelming majority have Norse names. One part of the Rus' envoys swear to their pagan gods, while another part invoke the name of the Christian God, indicating that a substantial portion of the Rus' elite was Christianized.
Apart from Igor's wife Olga, two other archontesses are mentioned: Predslava, Volodislav's wife and Sphandra, Uleb's wife. It is not clear whether these two pairs of names (Slavic and Norse respectively) refer to some Rurikid relatives of Igor or represent a separate ruling family.
The treaty of 944/945 repeated several clauses from the previous settlements. The Rus' promised not to attack Chersonesos, a Byzantine exclave in the Crimea (Article 8). The mouth of the Dnieper River (Beloberezhye) was to be administrated jointly, although the Rus' were forbidden to winter there and to oppress fishers from Chersonesos (Article 12).
Article 2 contains novel provisions on maritime law. In order to distinguish peaceful merchants from raiders, each ship of the Rus' was to bear a charter of the Kievan prince, explaining how many people and how many ships would sail to Constantinople. Otherwise, the Rus' ships might be apprehended by the imperial authorities.