Turkic combination Uz + Bek="own boss, master".
Uzbek (Öz-Beg) - the name of Khan's Golden Horde, (1282-1341, reign 1313-1341) where Islam was the main religion of the Golden Horde. Sultan Uzbek was the longest-reigning khan of the Golden Horde, under whose rule the state reached its zenith. He was succeeded by his son Jani Beg.
He was the son of Toghrilcha and grandson of Mengu-Timur, who had been khan of the Golden Horde from 1267-1280.
In the 60s of the XIV century the ethnonym "Uzbek" was the collective name for the Turco -Mongolian peoples.