JING'AN, Jiangxi, July 1 (Xinhua) -- Chinese archaeologists have started to excavate a 2,500-year-old tomb containing 47 coffins made of a rare wood called nanmu in east China's Jiangxi Province.

    The tomb, in Lijia village in Jing'an county, is 16 meters long, about 11.5 meters wide and three meters deep. It is believed to date back to the Eastern Zhou Dynasty (770-221 B.C.).

    It is the largest group of coffins ever discovered in a single tomb and the excavation has been dubbed "the most important archaeology project of the year" by cultural experts and media.

    Nine coffins were opened by archaeologists earlier because they were rotten and partly destroyed by tomb robbers. Archaeologists opened another coffin on Sunday morning, finding a relatively complete human skeleton, bodily tissue, as well as many bronze, gold and silk items, porcelain and jade.

    The bodily tissue has been identified as the brain of the dead in the coffin. The tissue has shrunk to the size of a fist, but it has complete brain structure with two cerebral hemisphere, cerebel, and brainstem.

    "This is the first time that such a complete structure was found in southern China and it will fill in gaps in the study of human bone structure in the pre-Qin era (770-221 BC)," said Zhu Hong, a palaeoanthropological expert from Jilin University.

    Zhu said the unique burial style could explain why the skeleton and the brain tissue were preserved so well in an area where the soil was acidic and unfavorable for preservation of human body.

    The coffins were made from halved nanmu, a rare and extremely durable wood, and covered in a layer of loess. They were fire-heated to make them solid, pressurized and waterproof.

    "The coffins were closely-sealed and there was little oxygen in there for bacteria to reproduce," said Zhu.

    The coffins, 2.5 to 2.8 meters long and 0.5 meters wide, were laid out side by side in an orderly fashion. They are being transported to a nearby storehouse to be kept in a temperature and humidity-controlled environment.

    Archaeologists have taken 13 coffins to the storehouse and opened 11 of them. They are to open more coffins in the next few days and more skeletons are expected to be found.

    The main coffin, weighted about two tons, will be opened at about 9 a.m. Monday at the tomb as it is too big to move.

    A group of cultural, palaeoanthropological, geological and forestry and archeological experts across China have arrived at the site for a joint research project.

    Experts will pinpoint the gender and ages at the time of death, and will further identify the causes of their death, their identities, their burial date and why they were buried together, said Fan Changsheng, director of the Jiangxi Provincial Institute of Archeology.

    The discovery could provide valuable clues to the study of social customs, funeral rites and lifestyles in the area, experts said.