Barley Field (IMAGE) Washington University in St. Louis Caption Prehistoric peasant farmers expanded the cultivation of domestic grains into extreme climate regions of the Old World, such as this barley field in Zuoni County, Gannan Tibetan Autonomous Prefecture. Credit Xinyi Liu/Washington University in St. Louis Usage Restrictions None License Licensed content Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.