Turkestan was at one time ruled by Emperor Gustasp.. Gustap reigned at the time of Zoroaster's birth, which is prior to 583 B.C. Additional documents indicate that Turkestan's history dates back to at least the third millennium BC. Many artifacts were produced in that period, and much trade was conducted. The region was a focal point for cultural diffusion, as the Silk Road traversed it. Turkestan covers the area of Central Asia and acquired its "Turkic" character from the 4th to 6th centuries AD with the incipient Turkic expansion.
Turkic sagas, such as the Ergenekon legend, and written sources such as the Orkhon Inscriptions state that Turkic peoples originated in the nearby Altay Mountains, and, through nomadic settlement, started their long journey westwards. Huns conquered the area after they conquered Kashgaria in the early 2nd century BC. With the dissolution of the Huns' empire, Chinese rulers took over Eastern Turkestan. Arab forces captured it in the 8th century. The Persian Samanid dynasty subsequently conquered it and the area experienced economic success. The entire territory was held at various times by Turkic forces, such as the Göktürks until the conquest by Genghis Khan and the Mongols in 1220. Genghis Khan gave the territory to his son, Chagatai and the area became the Chagatai Khanate. Timur took over the area in 1369 and the area became the Timurid Empire
