Tunay

Etymology
. Could refer to the Don river. According to I. M. Miziev Dunay or Tunay is from 'Tynay', from the Turkic root word 'tyn' meaning 'quiet'. H. M. Hubey adds the possibilities that the word is related to Turkic 'Deniz'/Tengiz' ('sea'), which is well established in other forms like 'tenger' (in Lir-Turkic and Hungarian), 'tong'/'don' ('to freeze'), and 'tang'/'tan' ('heavens'), so the root also seems to refer to 'large bluish expanse'. Tengri, or Tanrı means 'sky god'.

Moreover, Hubey insists on a relation to 'eridanus' ('large bodies of water') mentioned by Herodotus in his reports about certain nomadic tribes dwelling around the Pontic–Caspian steppe. According to Hubey the first syllable could refer to Turkic 'iri' or 'iriġ' ('large').