"...in an area where rain is scarce they were the first to practice a primitive form of irrigation agriculture, using the Tigris floods to water their fields and grow wheat, barley and linseed. The yield must have been substantial if the large and empty buildings found at various levels were really 'granaries' as has been suggested."
Georges Roux, Ancient Iraq, p. 54. Section titled, "The Samarra Period."
(Citation for "Between the Rivers, Before the State.")