The Proto-Altaic language is a hypothetical extinct language that has been proposed as the common ancestor of the disputed Altaic languages. In the 18th century, some similarities between the Turkic, Mongolian, and Tungusic languages led to the conjecture that they would be a single language family with a common ancestral language. Starting in the 19th century, some linguists proposed to include also the Japonic and/or Koreanic languages as well as the Ainu language, forming what would later be called the "Macro-Altaic family" (the original one being then dubbed "Micro-Altaic"). Around the same time others proposed to include the Uralic languages in a Ural-Altaic family.