The Kipchak language was an extinct Turkic language of Kipchak-Bolghar group.
Siberian Tatars was remaints of Eastern Kipchak tribes lived in Northern Kazakhstan in 10th century, but migrated to Europe later. So, their language originate from pure Kipchak, but later was influenced by Volga Tatar language, which also partly originate from Kipchak.
The remnants of Kipchak language are the most of Turkic languges in Eastern Europe and Caucasus. It seems to be true, because this language was a lingua franca in Golden Horde, conquered all this lands. Bolgar language-speaking Volga Bulgarians (or Kazan Tatars), Astrakhan Tatars , Balkars, Bashkirs and Mongolian aristocracy adopted to Kipchak langauge in Golden Horde. So modern Tatar language of Kazan Tatars and other languages appeared.
