Tibetans can thank barley for allowing their ancestors to live at higher altitudes, according to new research published in the journal Science.

Also known as the “roof of the world,” the Tibetan Plateau featured frigid temperatures that discouraged early humans from going above 8,200 feet above sea level, at least for permanent settlements. But about 3,600 years ago, the locals were introduced to a western frost-resistant crop: barley, according to the Washington Post.

Researchers found burnt seeds from early Tibetans at high elevations during that era. At that time, crops from different parts of Asia were merging at once, according to Martin Jones, a professor of archaeology at the University of Cambridge who authored the study. Foreign crops were introduced with old crops, adding another crop to the Tibetan farmer’s repertoire.

Their traditional staple at the time was millet, but once Tibetans moved farther up, they began to switch to barley, still an important part of Tibetans’ diets today. They also introduced sheep to their culture.

It was an important change because — unlike barley — millet could handle the brutal frosts at 11,000 feet, where researchers found settlements.

It was during this era that many crops began to circulate around the world. India discovered East Asian staples like rice, and crops from Africa moved to other countries.

Scientists believe that simply discovering barley probably wouldn’t have been enough to sustain early Tibetans at such high altitudes — they would have probably needed genetic changes as well. However, researchers believe that these genetic adaptations had already happened, which allowed Tibetans to live at the margins of high altitudes to begin with.

Ironically, the shift to higher elevations coincided as temperatures were dropping across the region, but that hardship didn’t stop Tibetans from making the move. It’s possible that the drop in temperatures actually aided the move by forcing some to stake out new claims for land as life got harder in the region.

“Although you can’t exactly argue that the lowlands were so full there was no space, you can argue that society was changing and breaking off into different kinds of communities,” said Jones, the study author. “They were differentiating themselves. The ownership of land and resources was key.”

Today, barley has fallen behind among the cereal crops as wheat, rice, and corn lead the pack. But it certainly appears to play an important part of human history.

There is some evidence that humans existed in the higher elevation areas as far back as 20,000 years ago, but scientists don’t think permanent settlements happened until much later. It was about 5,200 years ago when people started to establish more permanent residences at around 8,200 feet above sea level, which would have been the upper limit for farmers who grew millet.

Barley was able to supply settlers with a robust food that would last even during the wintertime, making it perfect for Tibetans.

Barley, a member of the grass family, was one of the first cultivated grains and grows in a wide variety. In addition to the Tibetans, peasants in Medieval Europe relied on barley. It was also used as animal fodder and as a material for the crafting of beer and distilled beverages.

In 2007, 136 million tons of grain were produced, placing it fourth among the major cereal crops. About 219,000 square miles are used worldwide to cultivate it.

Barley originates from an Old English word, which essentially means “flour.” The word “barn” originally meant “barley-house” and is derived from the grain.