BEIJING - TABOO subjects including the sex life of eunuchs, and the agonising castrations they endured, have finally been revealed.

The turbulent life of Sun Yaoting, China's last eunuch, has been recorded in the book The Last Eunuch of China, by amateur historian Jia Yinghua reports said on Monday.

It unveils an arcane society, lifting the lid on taboos like the sex life of eunuchs and the emperor they served, often lethal castrations that were frequently done at home and the incontinence and shame that came with the promise of great power.

For centuries in China, the only men from outside the imperial family who were allowed into the Forbidden City's private quarters were castrated ones. They swapped their reproductive organs for a hope of exclusive access to the emperor.

Sun's impoverished family made him a eunuch in the hope he would become a powerful political player. But history played the first of a series of cruel tricks on him - the emperor he hoped to serve had abdicated several weeks earlier.

"He was castrated, then the emperor abdicated. He made it into the Forbidden City, then Pu Yi was evicted. He followed him north and then the puppet regime collapsed. He felt life had played a joke at his expense," Jia said.

China's last eunuch was ultimately feted and valued, largely for outlasting his peers to become a unique relic and a piece of "living history'.

"He was conflicted over whether to tell the secrets of the emperor," said Jia. "I was the only person he trusted. He did not even confide in his family, after they threw away his 'treasure' (eunuch slang for their preserved genitals)," Jia said.

"He only cried about two things; when telling me about the castration and about the loss of his 'treasure'."

Sun died in 1996, in an old temple that had become his home. -- Reuters