richest in the world; for Irak is an immense alluvial delta, more than
five hundred miles from end to end, which the Tigris and Euphrates have
deposited in what was originally the head of the Persian Gulf. The Arabs
call it the _Sawâd_ or Black Land, and it is a striking change from the
bare ledges of Arabia and Iran which enclose its flanks, and from the
Northern steppe-land which it suddenly replaces--at Samarra, if you are
descending the Tigris, and on the Euphrates at Hit. The steppe cannot
compare with the _Sawâd_ in fertility, but the _Sawâd_ does not so
readily yield up its wealth. To become something better than a
wilderness of dust and slime it needs engineering on the grand scale and
a mighty population--immense forces working for immense returns. In a
strangely different environment it anticipated our modern rhythm of life
by four thousand years, and then went back to desolation five centuries
before Industrialism (which may repeople it) began.

The _Sawâd_ was first reclaimed by men who had already a mastery of
metals, a system of writing, and a mature religion--less civilised men
would never have attempted the task. These Sumerians, in the fourth
millennium B.C., lived on _tells_ heaped up above flood-level, each
_tell_ a city-state with its separate government and gods, for
centralisation was the one thing needful to the country which the
Sumerians did not achieve. The centralisers were Semites from the
Arabian plateau. Sargon of Akkad and Naram Sin ruled the whole _Sawâd_
as early as 2500 B.C.; Hammurabi, in 1900, already ruled it from
Babylon; and the capital has never shifted more than sixty miles since
then. Babylon on the Euphrates and Bagdad on the Tigris are the
alternative points from which the _Sawâd_ can be controlled. Just above
them the first irrigation canals branch off from the rivers, and between
them the rivers approach within thirty-five miles of each other. It is
the point of vantage for government and engineering.