Barley is currently the most cultivated crop in Spain, with an acreage of about three million ha. Its importance stems from its adaptation to areas with poor soil conditions and water stress. The aim of this work is to describe the historical evolution of barley types and varieties of barley grown by farmers in Spain. A historical review was performed by consulting articles and books on the history, archaeology, and agronomy related to the issue. Different web sites and articles about the current varietal state of barley in Spain were also consulted. Another important information source was the CRF (Centro de Recursos Fitogenéticos, Spanish Center of Plant Genetic Resources) of Spain, where a large collection of landraces is preserved. The first barleys came to Spain approximately 7600 years BP. The crop spread throughout the country, and the cultivation of barley was reported by the Romans, Arabs, Castilians, and Spaniards. At the beginning of the nineteenth century, the first attempt at classification was carried out. Until the 1940s, most barley acreage was sown with ancient landraces, but from that period up to the present, a steady varietal renovation occurred. The history of barley types and varieties in Spain is rich, and an extensive set of landraces is preserved in seed banks. These landraces contain genes for resistance and tolerance to biotic and abiotic stresses.