The earliest evidence of dry farming dates back to the Neolithic period, around 8000 BC. At this time, dry farming was practiced in the Middle East and North Africa, where rainfall was scarce and farmers relied on irrigation. By 3000 BC, dry farming had spread to Europe and Asia, and it was also being practiced in the Americas. Dry farming remained the dominant form of agriculture until the 20th century, when it was largely replaced by irrigated farming. However, dry farming is still practiced in some areas of the world where water is scarce or expensive.