Kiev - Wikipedia, the free encyclopedia

Происхождение первой русской столицы - Киева, черезвычайно сложное и спорное
But I'm not sure that I've got the meaning of the English phrase correctly

Also you can't really say Russian because that time the country was called Русь - http://ru.wikipedia.org/wiki/Русь
And if we talking about Русь then Киев is not the first state