The Viking nobleman, Rurik, was a massive Norseman who terrorized countries murdering, plundering, and destroying anything or anyone who opposed him. In the 9th century Rurik and the Vikings were traveling around by boat murdering, pillaging, and incinerating villages. They would sell the slaves and plunder in Constantinople. He raided what is now Russia, England, Germany, and Ireland.
At this point in history, present day Russia-Ukraine had a city called Novgorod that was a wealthy trading city. Three or four powerful groups of businessmen began fighting in Novgorod over trading rackets and causing each other major problems. It got so bad, that one of the businessman groups called on Rurik for reinforcement. So, Rurik came and brought his two brothers and 10,000 men to fight.
Since he defeated the groups, he looked around and realized he could take over himself. So, he did just that in 862 and declared himself Iron-Fisted Autocrat Now and Forever. He named his new empire after his Viking tribe, Rus. Thus, Russia became so.