Barley helped ancient Tibetans settle high elevations LHASA, Tibet, Nov. 20 (UPI) -- The Tibetan Plateau -- the so-called roof of the world -- and its thousands of glaciers supply millions of people throughout Asia with clean, fresh drinking water. It provides a steady flow to almost all of Asia's major rivers. But though life-giving, the plateau itself isn't exactly a welcoming place. It's cold and often barren. Now, thanks to a new study, scientists know how it was settled. The key was a hardy grain -- now a staple of health food stores -- called barley. It was barley's ability to stave off the cold, thin air of the Himalayas, researchers say, that first allowed the earliest settlers of the Tibetan Plateau to persist at elevations as high as 10,000 feet. "As barley is frost hardy and cold-tolerant, it is growing very well on the Tibetan Plateau even today," Fahu Chen, an archaeologist at Lanzhou University in China, told The New York Times in an e-mail. Barley agriculture could provide people with enough sustained food supplies even during wintertime. Chen led a team of archaeologists to uncover and analyze artifacts, including charred plant remains and stone tools, from 53 ancient sites scattered across the Tibetan Plateau. As detailed this week in a new paper published in the journal Science, researchers determined that ancient peoples of the Himalayas ascended to roughly 8,200 feet above sea level by about 5,200 years ago, or around 3200 BCE. But these early permanent settlements were still reliant on less hardy crops. By roughly 1600 BCE (3,600 years ago), lead study author Chen explained, settlers had begun cultivating barley and millet. These hardier grains allowed people to begin populating higher elevations. Around this time, the first permanent settlements at elevations of 10,000 feet appear. Chen told the Times that though hardier grains enabled the ancient move into thinner air, it was actually cooling temperatures that necessitated it. As global temperatures lulled some 5,200 year ago, limited resources forced populations to spread out. "People need to move to a new uninhabited region or improve technology to get enough food resources," Chen explained. In the case of the ancient people of Tibet, they did both.