The Discovery
The Dropa Disks were discovered in 1938 in the Baian-Kara-Ula mountains on the border that divides China and Tibet. In that year, an archeological expedition led by Chi Pu Tei (a professor at Beijing University) happened on some caves that had been occupied by primitive people. The caves themselves appeared to have been man-made, rather than natural.

Inside, the archeologists found an ancient burial site that contained some very intriguing remains. The skeletons were only about four feet in height, quite frail and supported skulls that seemed far too large for such delicate bone structures. It was initially suggested that the remains be that of apes, but that was easily discounted because only humans ritually bury the dead. On the walls around the graves were carved pictograms of the heavens: the sun, the moon, the stars, and the Earth with lines of dots connecting them.

The team found the most interesting discovery of all half buried in the dirt: stone disks, nine inches in diameter and three-quarters of an inch thick, with round three-quarter inch holes in the middle. Etched into the surface was a fine groove spiraling out from the center to the rim. The disk was obviously made by a human, or some other intelligent being.

The Facts
The disks (seven hundred and sixteen in total were found) were dated to be between 10,000 and 12,000 years old. Physically, the granite stones contained high concentrations of cobalt and other metals, making them very hard. When testing a disk with an oscillograph, a surprising oscillation rhythm was recorded as if the disks had once been electrically charged or had functioned as electrical conductors.

The continuous groove in each disk was not just a carved line, but a row of tiny hieroglyphics of no known language. The writing was allegedly deciphered by a Chinese scientist (Dr. Tsum Um Nui) in 1962. What he claimed to have found was considered so earth shattering, so controversial, that the Prehistory Department of the Beijing Academy prohibited the public release of the translation. Eventually though, it was published under the title "The Grooved Script Concerning Spaceships Which, as Recorded on the Discs, Landed on Earth 12,000 Years Ago."

The Story
The disks tell of a space probe from a distant planet that crash landed in the mountains. The occupants of the craft (the Dropa) took refuge in the mountain caves. The intentions of the Dropa were misunderstood by members of the Ham tribe who were occupying neighboring caves. These humans hunted the aliens and even killed some of them. A translation of one of the passages says: "The Dropa came down from the clouds in their aircraft. Our men, women, and children hid in the caves ten times before sunrise. When at last they understood the sign language of the Dropa, they realized that the newcomers had peaceful intentions...." The Dropa could not repair their spaceship and were then stranded on Earth.

Were the Dropa truly visitors from some distant planet, or is their story merely a creation myth imagined by a primitive culture? This question remains, for now, unanswered.

Interesting Side-note:
The area where the disks were found is actually inhabited by two groups of people that call themselves the Dropa and the Han. Anthropologists have been unable to categorize either tribe into any other known race; they are neither Chinese nor Tibetan. Both groups have an average height of about four feet. They have yellowish skin, are delicately boned and have heads that are disproportionately large for their bodies (very much like the skeletal remains found in the cave). Their eyes are not Asian in aspect, and have pale blue irises.

An ancient Chinese tale also tells of a small, yellow skinned, slender peoples who descended to the Earth from the clouds, and who were shunned by everyone because of their ugliness.

This information was excavated from:
http://paranormal.about.com/library/weekly/aa060198.htm