ASIA - In the middle of the 19th century, an area the size of Germany located between Beijing and Shanghai in central China was run for more than 15 years by the Nian rebels, a 50,000-strong network of bandit groups who lived by pillage and rape.

The Nian bandits were men without women which was long understood in China as the principal stimulus to their rebellion and cause of their violence. They originated in a district in northern China - Huai-pei - where the killing of infant girls to conserve food for more economically valuable boys in response to famine had been particularly terrible.

By 1850, the official records show there were 129 men to every 100 women, an astonishing imbalance in the ratio between the sexes. Lower-class Huai-pei peasants could not find wives; hungry, economically displaced and, in Chinese terms, "bare branches" - not proper men because they could not marry and father children - they turned to banditry as providing meaning and sustenance.

Those womanless bandits cast a long shadow over not just today's China, but the whole of Asia. Asia is estimated to suffer from up to 100 million missing women - aborted as foetuses or murdered in infancy because of their sex.

Pakistan, erupting in protests last week against President Musharraf's anti-democratic high-handedness in suspending a senior judge, is a volatile tinderbox where the capacity for such insurrection to spread is ever present.

Fanning the flames of injustice and Islamic fundamentalism is the country's sex imbalance. Dispossessed, displaced men with no prospect of ever finding a partner more readily take to the streets like Nian rebels; violence demonstrates masculine meaning.

In today's China, there are now 119 men for every 100 women. In some areas, the imbalance is greater than it was in Huai-pei in 1850. Earlier this year, an official Chinese report projected that by 2020, one in 10 men between 20 and 45 would be unable to find a wife. Professor Valerie Hudson of Brigham Young University in the United States estimates that by 2020, there will be 28 million surplus Chinese men and 31 million surplus Indian men.

Both governments are becoming more and more worried about the psychological and social consequences, not to mention the sheer criminality of it. As one Indian commentator remarks, the most dangerous period of a woman's life is her first few months in the womb.

China's President Hu Jintao, remembering the Nian rebellion, has publicly recognised that such a huge population of "bare branches" constitutes one of the biggest potential threats to the communist regime's survival. Real unemployment in China is more than 20 per cent, inequality is growing rapidly and there is plenty of injustice for rootless, violently inclined, womanless men to protest about.

For its part, the Indian government is increasingly alarmed by the explosion of woman trafficking and prostitution, and the threat to the rule of law implied by such mass infanticide and abortion of babies because of their sex. In the past few weeks, it has stepped up its campaign to make the battery of laws against such practices stick.