For thousands of years, nomadic tribes occupied vast lands beyond the limited reach of pre-modern empires. With the dawn of the modern age, these peoples found themselves locked inside the borders of powerful states whose drive to assimilate subject populations into homogenous national projects has led to a rapid dwindling of human cultural and biodiversity.   The Tarim Basin in northwest China has been home to the Turkic Uyghurs for over a thousand years, but the Chinese Communist Party has worked for decades to eliminate Uyghur cultural identity and demographic predominance. Perhaps no place on earth provides a more frightening example of modern methods and technology applied to man's darkest and most ancient impulses.