Varangians
Varangians did trade, piracy and mercenary activities. They move around using the river systems and portages of Gardariki.  The Gardariki was the areas north of the Black Sea. They had trade routes that connected Dark Age Europe with rich Arab Caliphates and the Byzantine Empire. Wanting the riches of Constantinople, Rus' Varangians started a number of Rus'-Byzantine Wars. Most of them, both in Byzantium and in Eastern Europe, were converted from paganism into Orthodox Christianity. Most scientific experts, including the ethnic Russian, Ukrainian and Belarusian people themselves, confirm the modern-day East Slavic ethnic group to be the direct, ancestral descendants of the Rus'.