the facts say, that all contemporaries who knew Chingis-Khan and his tribesmen, called them "Tatars". And, it’s most important - the tribesmen of Genghis Khan also called themselves "Tatars". “Chinghis-Khan and his tribesmen didn't speak the language, which we now call "Mongolian” (Russian orientalist V.Vasiliev,19-th c.). This's confirmed by many facts. See in the book "Forgotten Heritage of Tatars" (by Galy Yenikeyev).