History of Mesopotamia thereby incorporating not only parts of Syria but also almost all of Iraq and southeastern Turkey. The neighbouring steppes to the west of the Euphrates and the western part of the Zagros Mountains are also often included under the wider term Mesopotamia. A further distinction is usually made between Upper or Northern Mesopotamia and Lower or Southern Mesopotamia. Upper Mesopotamia, also known as the Jezirah, is the area between the Euphrates and the Tigris from their sources down to Baghdad. Lower Mesopotamia is the area from Baghdad to the Persian Gulf. In modern scientific usage, the term Mesopotamia often also
Agriculture in ancient Mesopotamia east, rising from 200-500 m in altitude, and which are now known as Jazirah (from the Arabic, "al-jazayra", 'the island'). Thus, the rivers flow through valleys which are 1-10 km wide. The southern half of Mesopotamia, which is the part properly called Mesopotamia from a geophysical point of view, since it is where the Tigris and Euphrates flow close to one another, is a vast plain, which is 150-200 km wide and has only a very slight incline, decreasing to the south until it is nearly non-existent. This encourages the development of river braiding, sudden changes of course, and the