Wikipedia
The Basmyls (Basmyl; Basmals, Basmils, Basmïl, ) were a 7th–8th century nomadic tribe who mostly inhabited the Dzungaria region in the northwest of modern-day China.
The Basmyls may be ancestral to the Argyn of the Middle Juz of modern Kazakhstan.
The Basmyls played a prominent role in the Turkic Khaganate from the 6th century, and at one time were the dynastic tribe who led the Khaganate. They later merged with Karluk and Yagma tribes and created the Kara-Khanid state. Basmyls were the first to use the term Idyk-kut, which replaced khagan in the titles of the Uyghur rulers of Turpan. The second component kut/qut in the title is often found in Old Turk onomastics and titulature and has the lexical meaning "grace of heaven" or "blessing".
In the year 720 CE, the dynastic Basmal clan were reported to be concentrated at Beitin (probably Bei Tun), near Gucheng (Qitai), in the Bogda Shan range, and to be Ashina Turks (Ch. 突厥 pinyin Tu-jue).
Mahmut Kashgari, an 11th century historian, lists the Basmyls as one of ten prominent Turkic tribes and enumerates the locations of the Turkic polities from the borders of Greece to the borders of China in the following sequence: Bechen ( Badjinak), Kyfchak ( Kipchak), Oguz, Yemek ( Kimek), Bashgyrt ( Bashkort), Basmyl, Kai, Yabaku, Tatars, Kyrgyz. Kashgari also noted that the Kai, Yabaku, Tatar, and Basmyl tribes are all bilingial, speaking Turkic alongside their own languages, while peoples including the Kyrgyzes, Kyfchaks, and Oguzes have their own Turkic languages, which are related to the languages of the Yemeks and Bashkirts.
The Basmals appear to be the "Argons" mentioned by Marco Polo in a country called "Tenduc" (around Kuku-Khotan, or modern-day Hohhot), during the 13th century. Polo reported that this tribe who had "sprung from two different races: to wit, of the race of the Idolaters of Tenduc and ... the worshippers of Mahommet. They are handsomer men than the other natives of the country, and having more ability, they come to have authority; and they are also capital merchants."