Barley was first domesticated in the area called the Fertile Crescent, where its wild progenitor Hordeum vulgare subsp. spontaneum still grows. Other centres of diversity of cultivated barley are found in Ethiopia and Morocco and parts of Asia. Wild relatives are distributed widely in Europe, Asia, Africa and the Americas.
Barley is grown from arctic latitudes to tropical areas and from sea level to high altitudes. In Tibet, Nepal, Ethiopia and the Andes, farmers cultivate barley at elevations higher than any other cereal. Barley predominates in the dry lands of North Africa, the Middle East, Afghanistan, Pakistan, Eritrea and Yemen. With such a widespread distribution, and with diverse uses that include human food, animal feed and as a raw material for alcoholic beverages, barley is the fourth most important cereal in the world.
The importance of barley as one of the original staple cereals is reflected in the number of accessions: more than 176,000 are listed in Genesys. Most of these are advanced materials, including released cultivars and research lines. About 22% are traditional varieties and landraces. Accessions are widely distributed among genebanks, with the largest collection holding only a third of the listed accessions. The global strategy for the ex situ conservation and use of barley germplasm identified 402,000 accessions held in 49 major collections worldwide.