<P> The Aramaic term biritum / birit narim corresponded to a similar geographical concept . Later, the term Mesopotamia was more generally applied to all the lands between the Euphrates and the Tigris, 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 . </P> <P> A further distinction is usually made between Northern or Upper Mesopotamia and Southern or Lower Mesopotamia . Upper Mesopotamia, also known as the Jazira, 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 and includes Kuwait and parts of western Iran . </P> <P> In modern academic usage, the term Mesopotamia often also has a chronological connotation . It is usually used to designate the area until the Muslim conquests, with names like Syria, Jazirah, and Iraq being used to describe the region after that date . It has been argued that these later euphemisms are Eurocentric terms attributed to the region in the midst of various 19th - century Western encroachments . </P> <P> Mesopotamia encompasses the land between the Euphrates and Tigris rivers, both of which have their headwaters in the Armenian Highlands . Both rivers are fed by numerous tributaries, and the entire river system drains a vast mountainous region . Overland routes in Mesopotamia usually follow the Euphrates because the banks of the Tigris are frequently steep and difficult . The climate of the region is semi-arid with a vast desert expanse in the north which gives way to a 15,000 square kilometres (5,800 sq mi) region of marshes, lagoons, mud flats, and reed banks in the south . In the extreme south, the Euphrates and the Tigris unite and empty into the Persian Gulf . </P>

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