Rurik the Great was a Varangian? warlord who lived in the 9th century A.D. He came down from the northlands, conquered the lands now known as the Principalities of Novgorod and Kiev, established strongholds at both cities, and founded the nation of Kievan Rus'. His tribe, the Rus, mingled with the Slavic peoples who inhabited the regions Rurik conquered, and the descendants of that mingling became the Russian people. Scions of the dynasty that Rurik founded rule the Russian Lands to this day (with the exception of Kiev, which has no prince).
In his campaign to conquer the Slavic lands along the River Dnieper, Rurik faced the most resistance from a necromancer called Damek the Black, who commanded an army of undead (as well as some mortal followers). Damek was ultimately defeated, but, with his undead army and his knowledge of dark magic, was a serious enough roadblock that Rurik considered any future necromancers to be a threat to the power of his dynasty. To prevent this, Rurik banned the practice of necromancy in all the lands under his rule; this ban has mostly persisted in the Russian lands to this day.