Original sentence: The ancestors of the Uyghur includes the nomadic Turkic Gaoche People and possibly the Tocharian peoples of the Tarim Basin.They are one of China's 56 officially recognized ethnicities, consisting of 8.68 million people according to the 2004 Chinese census
Edited sentence: The ancestors of the Uyghur were the nomadic Turkic Gaoche People and the Tocharian peoples of the Tarim Basin.They are one of China's 56 officially recognized ethnicities, consisting of 8.68 million people according to the 2004 Chinese census, but this may be an under-estimation