How did Russia become a country?
The short answer is the country of Rus became known as Russia after the Viking, Rurik and is band, which that was then called the "Rus" after the Slavs. The Rus was becoming powerful and became a country over time. (And battles, no doubt...to take over land) it was changed to Russia.
A Viking by the name of Rurik settled in Central Europe (along with other Vikings) where the Slavs already lived. The Slavs were a tribe that fought others to win land. But when Rurik and the other Vikings Invaders came, they were forced to obey.
The Slavs called the Viking Invaders the Rus because 'Rus' sounds like Rurik's name. As the Vikings and Slavs formed tribes, they and built their own cities and traded too. Over time, the Rus became powerful.
Instead of trading with Constantinople, the tribes of the Rus wanted to conquer it. Although the Rus were good Sailors, they were no match for Byzantine's "Sea Fire." (Also known as "Greek fire" is a chemical reaction.) One of the Rus princes named Vladimir made peace with Constantinople; he gave Rus warriors to the emperor, and married a Byzantine princess.