Domestication of sheep and goats reached Egypt from the Near East possibly as early as 6,000 BC. Graeme Barker states "The first indisputable evidence for domestic plants and animals in the Nile valley is not until the early fifth millennium bc in northern Egypt and a thousand years later further south, in both cases as part of strategies that still relied heavily on fishing, hunting, and the gathering of wild plants" and suggests that these subsistence changes were not due to farmers migrating from the Near East but was an indigenous development, with cereals either indigenous or obtained through exchange. Other scholars argue that the primary stimulus for agriculture and domesticated animals (as well as mud-brick architecture and other Neolithic cultural features) in Egypt was from the Middle East.