The civil strife in the Xinjiang region of northwestern China has been a stark reminder that China, despite the economic, military and diplomatic advances of the past three decades, is still a fragile empire that could break apart as it has periodically in the past.

Fighting between Uighurs and Chinese armed with clubs, knives and steel pipes left nearly 200 dead and 1,000 injured, and the Communist Party alarmed. President Hu Jintao abruptly left a G8 economic summit in Italy to hurry home, the People's Armed Police flooded the streets of the provincial capital in Urumqi, and the government's news agency, Xinhua, and the party's newspaper, People's Daily, appealed for national unity.

Beijing also sought to blame the U.S. for the violence. China Daily, Beijing's English language newspaper, asserted that the U.S. government "is massively intervening into the internal politics of China." The motive, the newspaper contended, arose from "the strategic location of Xinjiang" and its "importance for China's future economic and energy cooperation with Russia" and central Asian nations.

China's 50 to 55 minority groups make up less than 8 percent of the nation's population but are in critical areas along the country's periphery. Since the Han Dynasty 2,000 years ago, China has conquered nations and tribes to assemble the empire of the 21st century. The uprising in Tibet before the Beijing Olympics in 2008 reflected a wider unrest among the non-Chinese in the border regions.

Like the Uighurs, most of the minorities have their own languages and cultures and have not been integrated into Chinese society. The Uighurs are Muslims related to the Tajiks, Kazakhs, and other Turkic people of central Asia. Some Uighurs, like some Tibetans, seek independence from China but most would appear to be satisfied with more autonomy and less control from Beijing.

Perhaps the most intense grievance the Tibetans, Uighurs and other minorities have is that mainstream Chinese, with government and party encouragement, have been moving into Tibet and Xinjiang. These Chinese control local governments, have preference in jobs, and generally look down on the minorities.

Gideon Rachman, who writes about foreign affairs in the Financial Times in Britain, says "China's emotional and affronted reaction to the upheavals in Xinjiang is typical of an empire under challenge." He writes: "China is especially ill-equipped to understand ethnic nationalism within its borders because many government officials simply do not accept, or even grasp, the idea of "'self-determination.'"

"Yet the idea that Tibet and Xinjiang could aspire to be separate nations is by no means absurd," he says. Both experienced independence in the 20th century, he notes, pointing to a short-lived East Turkestan Republic in Xinjiang that was extinguished by the People's Liberation Army in 1949 and de facto independence in Tibet between 1912 and 1949.

Arthur Waldron, a scholar at the University of Pennsylvania who specializes in Chinese affairs, agreed but argued that Beijing's "biggest problems are with the Chinese — or Han — population. The thousands of demonstrations reported every year are overwhelmingly Han; dissent is spearheaded by the Han, and most importantly, given that the most powerful jobs in government and the most important roles in society are in their hands, the Han are the group that can make or break the communist government."

Several years ago in a tea shop in Shanghai, a Chinese editor drew a connection between the issue of Taiwan and the minorities in China. "I think Taiwan should be part of China," she said, "but it's not worth fighting over. What I worry about, if we let Taiwan go, then the Tibetans and the Uighurs and maybe others will want to leave China."

"If that happens," she lamented, "what will happen to my country?"

Richard Halloran, formerly a New York Times correspondent in Asia and in Washington, is a writer in Honolulu.