The precise date of the initial expansion from the early homeland remains unknown. The first state known as "Turk", giving its name to the many states and peoples afterwards, was that of the Göktürks ("gök" = 'blue' or 'celestial', however in this context "gök" refers to the direction "east". Therefore, Gokturks are the Eastern Turks) in the 6th century. In 439, the head of the Ashina clan led his people from Lijian (modern Zhelaizhai) to the Rouran seeking inclusion in their confederacy and protection from China. His tribe consisted of famed metal smiths and was granted land near a mountain quarry that looked like a helmet, from which they got their name Turk/Tujue 突厥. In 546, the leader of the Ashina, Bumin, aided the Rouran in putting down a Tiele revolt. Bumin requested a Rouran princess for his service but was denied, after which he declared independence. In 551, Bumin declared himself Khagan and married Princess Changle from Western Wei. He then dealt a serious blow to the Rouran Khaganate the next year, but died soon after. His sons, Issik Qaghan and Muqan Qaghan, continued to wage war on the Rouran, finishing them off in 554. By 568, their territory had reached the edges of the Byzantine Empire, where the Avars, possibly related to the Rouran in some fashion, escaped. In 581, Taspar Qaghan died and the khaganate entered a civil war that resulted in two separate Turkic factions. The Eastern Khaganate was defeated by the Tang dynasty in 630 while the Western Khaganate fell to the Tang in 657. In 682, Ilterish Qaghan rebelled against the Tang and founded the Second Turkic Khaganate, which fell to the Uyghurs in 744.