So grave was the crisis in western China that President Hu Jintao canceled a meeting with President Obama, broke off from the G8 summit and flew home.
By official count, 158 are dead, 1,080 injured and a thousand arrested in ethnic violence between Han Chinese and the Muslim, Turkic-speaking Uighurs of Xinjiang. That is the huge oil-rich province that borders Pakistan, Afghanistan and several Central Asian countries that seceded from the Soviet Union.
Uighur sources put the death toll much higher.
The Communist Party chief in Xinjiang has promised to execute those responsible for the killings.
In 1989, fear that what was happening in Eastern Europe might happen in Beijing produced Tiananmen Square. The flooding of Chinese troops into Xinjiang bespeaks a fear that what happened to the Soviet Union could happen to China. Unlike Mikhail Gorbachev, the Chinese, as they showed in Tibet, will wage civil war to crush secession.
Already, Beijing has struggled to ensure perpetual possession of Inner Mongolia, Xinjiang and Tibet -- half of the national territory -- by moving in millions of Han Chinese, swamping the indigenous peoples, as they did in Manchuria.
The larger issue here is the enduring power of ethnonationalism -- the drive of ethnic minorities, embryonic nations, to break free and create their own countries, where their faith, culture and language are predominant. The Uighurs are such a people.
Ethnonationalism caused the Balkan wars of 1912 and 1913, triggered World War I in Sarajevo, and tore apart the Austro-Hungarian and Ottoman empires. Ethnonationalism birthed Ireland, Turkey and Israel.
Ethnonationalism in the 1990s tore apart the Soviet Union and Yugoslavia, and broke up Czechoslovakia, creating two-dozen nations out of three. Last August, ethnonationalism, with an assist from the Russian Army, relieved Georgia of Abkhazia and South Ossetia.
Russia has its own ethnic worries in Chechnya, Dagestan and Ingushetia, whose Moscow-installed president was nearly blown to pieces two weeks ago and where a Chechen convoy was ambushed last week with 10 soldiers killed.
The ethnonationalism that pulled Ireland out of the United Kingdom in 1921 is pulling Scotland out. It split the Asian subcontinent up into Pakistan, India and Bangladesh. Iran, Iraq and Pakistan are all threatened.
Persians are a bare majority against the combined numbers of Azeris, Kurds, Arabs and Baluch. Each of those minorities shares a border with kinfolk -- in Azerbaijan, Kurdistan, Iraq and Pakistan.