The starting point of the Neolithic Period is much debated, as different parts of the world achieved the Neolithic stage at different times, but it is generally thought to have occurred sometime about 10,000 BCE. This point coincides with the retreat of the glaciers after the Pleistoceneice ages and the start of the Holocene Epoch. Archaeological evidence indicates that the transition from food-collecting cultures to food-producing ones gradually occurred across Asia and Europe from a starting point in the Fertile Crescent. The first evidence of cultivation and animal domestication in southwestern Asia has been dated to roughly 9500 BCE, which suggests that those activities may have begun before that date. Fertile Crescent, the region where the first settled agricultural communities of the Middle East and Mediterranean basin are thought to have originated by the early 9th millennium BCE. The term was popularized by the American Orientalist James Henry Breasted. The Fertile Crescent includes a roughly crescent-shaped area of relatively fertile land which probably had a more moderate, agriculturally productive climate in the past than today, especially in Mesopotamia and the Nile valley. Situated between the Arabian Desert to the south and the mountains of the Armenian Highland to the north, it extends from Babylonia and adjacent Elam (the southwestern province of Persia, also called Susiana) up the Tigris and Euphrates rivers to Assyria. From the Zagros Mountains east of Assyria it continues westward over Syria to the Mediterranean and extends southward to southern Palestine. The Nile valley of Egypt is often included as a further extension, especially since the short interruption in Sinai is no greater than similar desert breaks that disturb its continuity in Mesopotamia and Syria.