Why it's the capital
Moscow became the capital of the Grand Principality of Moscow, which led the unification of Russian lands in the 15th century. After two centuries with the capital elsewhere, Lenin moved it back to Moscow on 12 March 1918.
Capital of RussiaMoscow stands on the Moskva River in Central Russia, in the European part of a huge country that stretches all the way across North Asia to the Pacific.
Moscow became the capital of the Grand Principality of Moscow, which led the unification of Russian lands in the 15th century. After two centuries with the capital elsewhere, Lenin moved it back to Moscow on 12 March 1918.
Start at Minsk, the capital of Belarus, and go almost straight east, slightly north, into Russia. Moscow is there, nowhere near Russia's Asian side.
Saint Petersburg, on the Baltic Sea far to the northwest, was the capital from 1712 to 1918. Some players still tap it, but the capital is Moscow.
Sources: Wikipedia: Moscow, Wikipedia: Russia, Wikipedia: Saint Petersburg