All the men who were analyzed had a Y chromosome that is now mostly found in Eastern Europe, Central Asia and Siberia, but rarely in China. The mitochondrial DNA, which passes down the female line, consisted of a lineage from Siberia and two that are common in Europe. Since both the Y chromosome and the mitochondrial DNA lineages are ancient, Dr. Zhou and his team conclude the European and Siberian populations probably intermarried before entering the Tarim Basin some 4,000 years ago.

Image A 3,800-year-old mummy, the Beauty of Xiaohe, found at the Small River Cemetery. Credit... Wang Da-Gang

The Small River Cemetery was rediscovered in 1934 by the Swedish archaeologist Folke Bergman and then forgotten for 66 years until relocated through GPS navigation by a Chinese expedition. Archaeologists began excavating it from 2003 to 2005. Their reports have been translated and summarized by Victor H. Mair, a professor of Chinese at the University of Pennsylvania and an expert in the prehistory of the Tarim Basin.

As the Chinese archaeologists dug through the five layers of burials, Dr. Mair recounted, they came across almost 200 poles, each 13 feet tall. Many had flat blades, painted black and red, like the oars from some great galley that had foundered beneath the waves of sand.

At the foot of each pole there were indeed boats, laid upside down and covered with cowhide. The bodies inside the boats were still wearing the clothes they had been buried in. They had felt caps with feathers tucked in the brim, uncannily resembling Tyrolean mountain hats. They wore large woolen capes with tassels and leather boots. A Bronze Age salesclerk from Victoria’s Secret seems to have supplied the clothes beneath — barely adequate woolen loin cloths for the men, and skirts made of string strands for the women.

Within each boat coffin were grave goods, including beautifully woven grass baskets, skillfully carved masks and bundles of ephedra, an herb that may have been used in rituals or as a medicine.

In the women’s coffins, the Chinese archaeologists encountered one or more life-size wooden phalluses laid on the body or by its side. Looking again at the shaping of the 13-foot poles that rise from the prow of each woman’s boat, the archaeologists concluded that the poles were in fact gigantic phallic symbols.