The numbers alone convey the richness of what archaeologists found at Karuo: 1,060 stone artifacts, 1,284 pottery shards, and 4,755 bone objects. The site was in good enough condition to reveal not just individual objects but the infrastructure of daily life -- house foundations, roads, walls, and stone altars. The pottery bears a striking resemblance to pieces from Majiayao culture sites, particularly the later Machang and Banshan phases, but closer examination reveals that the Karuo potters used different manufacturing methods. The imitation was visual, not technical, suggesting that the people of Karuo were aware of cultures hundreds of kilometers away and borrowed their aesthetic ideas while maintaining their own craft traditions. Their tool assemblage also shows parallels with sites in western Sichuan, pointing to a web of connections across the plateau's eastern margins.

Thirty-four house foundations survived at Karuo, and their evolution across the site's occupation layers reads like a narrative of growing commitment to place. In the earlier phases, the houses were round and semi-subterranean -- simple shelters dug partially into the earth, the kind of dwelling a people still hedging their bets might build. Over time, the architecture shifted. Later houses were rectangular and fully subterranean, more solidly constructed, with clear evidence of greater investment in permanence. This transition from round to rectangular, from tentative to rooted, mirrors patterns seen at Neolithic sites across East Asia. At Karuo, it marks the moment a transient community became a village, deciding that this particular valley at this particular altitude was worth the effort of staying.

Foxtail millet was the staple that made Karuo viable. The oldest evidence for its cultivation at the site dates to around 3000 BC, and the people supplemented their harvest with hunting. Some broomcorn millet also turned up in the excavations, but since broomcorn requires even higher temperatures than foxtail millet to grow, it almost certainly arrived through trade with communities at lower elevations. This detail illuminates a crucial reality of life at Karuo: farming at 3,100 meters was not a self-contained enterprise but part of a wider exchange network that linked the high plateau to the warmer valleys below. The millet itself was a bet on climate -- foxtail millet needs warmth, and Karuo existed during a period of elevated temperatures that made cultivation just barely possible at this altitude.

Around 1750 BC, the residents of Karuo abandoned their settlement. The departure appears to have been abrupt, and the most likely explanation is climate. Karuo had coincided with a warm period that pushed temperatures high enough for foxtail millet to mature at 3,100 meters. When cooler conditions returned, the margin disappeared. A degree or two of average temperature change was enough to make the difference between a harvest and a failed crop at this altitude. The community that had spent more than a thousand years building houses, firing pottery, and working bone simply left. No successor settlement replaced them. The site lay undisturbed until Chinese archaeologists arrived in 1977, finding a Neolithic village preserved beneath millennia of Tibetan soil -- a time capsule from the era when humans first proved they could live, and farm, on the plateau.