Hytay应该是古代某个突厥部落的名字,不知道为什么会变成对汉人的称呼,也许是突厥语中对中国的称呼。
摘自http://sophistikatedkids.com/turkic/20Roots/ZakievGenesis/ZakievGenesis3-18En.htm
The third type of Türks are those Türkic-speaking tribes and peoples, whom Mahmut Kashgarly in his work "Divanu lugat-it-türk" (11th century) regards as Türks. Their list: Afshar, Aramut, Argu, Ava (Awа), Basmyl, Bashgirt, Ajat, Baündar, Bechenek, Bulak, Bulgar, Büdgüz, Charuklug, Chigil, Chomal, Chivaldar, Eymür, Halach, Khazar, Hytay, Ygrak, Karluk, Kar Yagma, Kay, Kaiyg, Kenchek, Kyfchak, Kynyk, Kyrgyz, Küchet, Ograk, Oguz (Uguz), Salgur, Sogdak, Suvar, Tat, Tatar, Tavgach, Tengüt, Tokhsi, Tutyrka, Tüger, Türk, Türkmen, Ugrak, Uigur, Uregir, Yabaku, Yagma, Yasmyl, Yava, Yаwа, Yazgyr, Yemek, Yywа, Yuregir. Of the listed Türkic tribes some people preserved their own ethnonym, and some people lost it and became part of other Türkic tribes and peoples.