Rivers. Or more precisely the great rivers in Eastern Europe from here to the Volga - Danube, Dniester, Dnieper, Don -, their name apparently is the result of Scythian laziness who called all of them danu = river...
Our first chronicle, the nameless one, called Scythia Dentumoger, a big country spreading to the east as far as the Don. Supposedly the Dentu = Don.

Other rivers are called river, I'm gonna write some in my next post.