plateau or table-land. West of the favored district, the Arabian and
African wastes are seas of sand, seldom raised much above, often sinking
below, the level of the ocean; while east of the same, in Persia, Kerman,
Seistan, Chinese Tartary, and Mongolia, the desert consists of a series
of plateaus, having from 3000 to nearly 10,000 feet of elevation. The
green and fertile region, which is thus interposed between the "highland"
and the "lowland" deserts, participates, curiously enough, in both
characters. Where the belt of sand is intersected by the valley of the
Nile, no marked change of elevation occurs; and the continuous low desert
is merely interrupted by a few miles of green and cultivable surface, the
whole of which is just as smooth and as flat as the waste on either side
of it. But it is otherwise at the more eastern interruption. There the
verdant and productive country divides itself into two tracts, running
parallel to each other, of which the western presents features not unlike
those that characterize the Nile valley, but on a far larger scale; while
the eastern is a lofty mountain region, consisting for the most part of
five or six parallel ranges, and mounting in many places far above the
level of perpetual snow.

It is with the western or plain tract that we are here concerned.
Between the outer limits of the Syro-Arabian desert and the foot of the
great mountain range of Kurdistan and Luristan intervenes a territory
long famous in the world's history, and the chief site of three out of
the five empires of whose history, geography, and antiquities it is
proposed to treat in the present volumes. Known to the Jews as
Aram-Naharaim, or "Syria of the two rivers;" to the Greeks and Romans as
Mesopotamia, or "the between-river country;" to the Arabs as Al-Jezireh,
or "the island," this district has always taken its name from the
streams, which constitute its most striking feature, and to which, in
fact, it owes its existence. If it were not for the two great