The Tigris-Euphrates Valley. Mesopotamia appears to have
been populated towards the end of its Neolithic period by
invaders both from the poor grasslands to the south and from
the mountains and plateaux to the north. The group of cities
near the head of the Gulf, chief among which were Ur and
Eridu, were founded by the Sumerians, a bronze-using people
who possibly arrived from the east. Up-stream was Akkad, a
group of cities "founded by Akkadian settlers from the south,
perhaps mainly Semitic. Th_ city states of the lower
TigrisEuphrates valley were welded into a single state by the
first of the world's conquerors, Sargon of Akkad, whose
authority  reached from the Persian Gulf to the Mediterranean.
Such a
union was justified by the necessity, as in Egypt, for some
measure of joint control over the rivers and irrigation systems,
and also by the continual threat of attack from desert nomads to
the south and from Elamites, Hittites, and other peoples to the
north. The Sumero-Akkadian rule was, in fact, terminated by a
fresh invasion of the northern steppe people, who established in
2169 B.C. the first Babylonian dynasty. The city of
Babylon had been one of many Akkadian towns of the plain. It
lay originally to the west of the Euphrates and, probably for this
reason, had been of small importance. Now, however, the
course of the Euphrates changed, deserting Agade, Kish, and
Nippur, to flow past the walls of Babylon.
Mesopotamia was no less dependent on trade than Egypt.

The raw materials of its growing industries, copper ore,
precious and semi-precious stones, marble and other stones for
building, timber, and even certain foodstuffs, had to be
imported. They came from the hills of Armenia, from Syria,
Palestine, and Asia Minor. The trade-route ran up the Tigris
valley and, in the vicinity of the present town of Mosul, struck
westward along the mountain foot towards the gaps in the
Amanus mountains. The town of Assur grew up here, where the
land route left the river; Nimrud and Nineveh, were later
established further up-stream. Westward along the Fertile
Crescent lay the trading towns of Nisibin, Carchemish, and
Harran. Thus was founded by about 2000 B.C. the first
Assyrian state, at once a commercial dependency .of Babylonia
and a 'march' state, protecting the exposed north-western
frontier of the latter. The first Babylonian dynasty was
terminated in 1870 B.C. by fresh invasions from the North, this
time by the Hittite people, who had established an empire in
Asia Minor, with its capital at Boghaz Keui, in the valley of
the Halys riv:er. Babylon recovered its political power, and,
guided by the extent of the" Fertile Crescent," conquered
westward into Palestine. Then Babylon was overthrown by the
Assyrians, who, on their exposed northern frontier had
cultivated the arts of war, whereas the Babylonians had for
centuries been engrossed in problems of irrigation and
cultivation. Another invasion of Mesopotamia about 540 B.C.
sub_ .
jected the area to the Medes and Persians. These people, with
whom the tribes north of the Zagros mountains for the first time
achieved political unity, conquered the whole Fertile Crescent,
and, unlike other conquerors of the Tigris-Euphrates valley,
were not stopped by the Taurus mountains (Fig. 6). . Instead
they ascended through the Cilician passes on to the
plateau, overthrew the Hittite state, advanced to the Sea of
Marmora and crossed into Europe. Thus political conquest was
reaching outward from the valleys of Mesopotamia, as the
spread of culture had done.

                GEORGE G HARRAP, LONDON; 1947. PGS 32-40.