By Rupert Wingfield-Hayes
BBC News, Beijing
Police in China are investigating whether the discovery of more than 120 human skulls may be part of a growing trade in macabre handicrafts.
The skulls were found in late March
The skulls were found last week wrapped in plastic bags and dumped in a ravine on the edge of the Tibetan plateau.
All of the skulls were missing their top half, which appeared to have been sawn off.
China's media and internet have buzzed with wild speculation about the grizzly discovery in the remote north-west.
Are the bags full of sawn-off skulls the gruesome product of a mass murderer or perhaps the detritus of some grim medical experiment?
Both have now been ruled out. The most likely answer is, if anything, even more bizarre.
Artefacts in demand
Investigators think the skulls are the leftovers from a surging industry in ghoulish handicrafts.
The 121 hacked up skulls were dumped close to the borders of Tibet. Ceremonial bowls made from human skulls have a long tradition in some branches of Tibetan Buddhism.
The huge growth in tourism to Tibet has apparently led to an equally large increase in demand for Buddhist artefacts.
In the markets of Lhasa, bowls made from fake skulls sell for two or three pounds each. But bowls made from genuine human skulls are said to fetch hundreds of pounds.
The question that so far no one has been able to answer is where did the skulls come from in the first place, and did their owners die from natural or unnatural causes?