Why was the Byzantine Empire the most attractive and accessible to the Rus?

Eastern tribes gravitated towards Eastern civilization in the initial period of their existence. They preferred to trade and build diplomatic relations with the Byzantine Empire, because it was at a higher level of development. Byzantium at that time was already a Christian center, therefore it was of interest to pagan tribes. Russian tribes went to this state with an army in order to get more resources and products of artisans, because they were famous for their quality and diversity.