"The 2,900-year-old Tibetan Tripitaka states clearly why and how brain surgery was carried out," said Karma Trinley, an associate professor from the Tibetan language and literature department of Tibet University in Lhasa, capital of southwest China's Tibet Autonomous Region.

Karma Trinley, an avid researcher and reader of classic Tibetan literature, Buddhism and calligraphy, began studying the Tripitaka in 1970. "It describes in detail how a young Indian doctor watched brain surgery being performed by a veteran surgeon," he said.

The young Indian doctor, whose name was similar in pronunciation to the Tibetan name Tsogyel, was not allowed to join the surgery, but merely stood by with the patient's permission, according to the Tripitaka.

The book said that the patient was suffering from a severe headache and repeatedly knocked his head on hard objects to ease the pain.

When Tsogyel saw the surgeon trying to operate on the patient's brain with a pair of tweezers, he shouted that the tweezers had to be heated first.

"Tsogyel was a well-reputed doctor and was good at all medical practice except brain surgery," said Karma Trinley. "But the surgeon followed his advice and the surgery later proved successful."

He said Tsogyel's advice on sterilization helped raise the success rate of surgery at the time. Tsogyel later became a skilled surgeon himself.

The Tripitaka is the earliest collection of Buddhist writings. The information contained in the writings was originally passed down orally, and was finally written down in the third century B.C.

The Tibetan Tripitaka was translated from Sanskrit language of ancient India. It contains two parts, the Gangyur and the Dangyur.

The Gangyur is a collection of teachings of Sakyamuni, the founder of Buddhism, adopted by his disciples after his death.

The Dangyur is a collection of notes and interpretations on the Gangyur, provided by Indian and Tibetan Buddhist masters, scholars and translators. It covers philosophy, logics, literature, linguistics, art, astronomy, medicine, architecture and calendar calculation.

"The Tibetan Tripitaka contains Sakyamuni's classifications of 440 ailments that were believed to be associated with wind, bile and phlegm, and were categorized accordingly," said Karma Trinley.

He added that many of the medical theories in the book are still used by Tibetan doctors today.

Evidence of ancient brain surgery was first found in 1998, when archeologists unearthed human skulls with mended cracks on the Qinghai-Tibet Plateau. These cracks indicated that craniotomies were probably performed by the Chinese over 5,000 years ago.

Before the Tibetan Tripitaka's description of brain surgery was discovered, researchers used to disagree on the purpose of ancient craniotomies, said Karma Trinley.

"Some believed it was a religious ritual to dispell evils or bring happiness, while others held that it was a therapy used by witches and wizards," he said.