Bronze Age around 1800 BC. These people may have been of Tocharian origin, and some have suggested them to be the Yuezhi mentioned in ancient Chinese texts. The Tocharians are thought to have developed from the Indo-European speaking Afanasevo culture of Southern Siberia (c. 3500–2500 BC). A study published in 2021 showed that the earliest Tarim Basin cultures had high levels of Ancient North Eurasian ancestry, with smaller admixture from Northeast Asians. Uyghur activist Turgun Almas claimed that Tarim mummies were Uyghurs because the earliest Uyghurs practiced shamanism and the buried mummies' orientation suggests that they had been shamanists; meanwhile, Qurban Wäli claimed words written in Kharosthi and Sogdian scripts as "Uyghur" rather than Sogdian words absorbed into Uyghur according to other linguists. Later migrations brought peoples from the west and northwest to the Xinjiang region, probably speakers of various Iranian languages such as the Saka tribes, who were closely related to the European Scythians and descended from the earlier Andronovo culture, and who may have been present in the Khotan and Kashgar area in the first millennium BC, as well as the Sogdians who formed networks of trading communities across the Tarim Basin from the 4th century AD. There may also be an Indian component as the founding legend of Khotan suggests that the city was founded by Indians from ancient Taxila during the reign of Ashoka. Other people in the region mentioned in ancient Chinese texts include the Dingling as well as the Xiongnu who fought for supremacy in the region against the Chinese for several hundred years. Some Uyghur nationalists also claimed descent from the Xiongnu (according to the Chinese historical text the Book of Wei, the founder of the Uyghurs was descended from a Xiongnu ruler), but the view is contested by modern Chinese scholars. The Yuezhi were driven away by the Xiongnu but founded the Kushan Empire, which exerted some influence in the Tarim Basin, where Kharosthi texts have been found in Loulan, Niya and Khotan. Loulan and Khotan were some of the many city-states that existed in the Xinjiang region during the Han Dynasty; others include Kucha, Turfan, Karasahr and Kashgar. These kingdoms in the Tarim Basin came under the control of China during the Han and Tang dynasties. During the Tang dynasty they were conquered and placed under the control of the Protectorate General to Pacify the West, and the Indo-European cultures of