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 rivers—­the Tigris and Euphrates—­with their tributaries, the more northern part of the Mesopotamian lowland would in no respect differ from the Syro-Arabian desert on which it adjoins, and which in latitude, elevation, and general geological character it exactly resembles.  Towards the south, the importance of the rivers is still greater; for of Lower Mesopotamia it may be said, with more truth than of Egypt, that it is “an acquired land,” the actual “gift” of the two streams which wash it on either side; being, as it is, entirely a recent formation—­a deposit which the streams have made in the shallow waters of a gulf into which they have flowed for many ages.

The division, which has here forced itself upon our notice, between the Upper and the Lower Mesopotamian country, is one very necessary to engage our attention in connection with the ancient Chaldaea.  There is no reason to think that the terns Chaldaea had at anytime the extensive signification of Mesopotamia, much less that it applied to the entire flat country between the desert and the mountains.  Chaldaea was not the whole, but a part of, the great Mesopotamian plain; which was ample enough to contain within it three or four considerable monarchies.  According to the combined testimony of geographers and historians, Chaldaea lay towards the south, for it bordered upon the Persian Gulf; and towards the west, for it adjoined Arabia.  If we are called upon to fix more accurately its boundaries, which, like those of most countries without strong natural frontiers, suffered many fluctuations, we are perhaps entitled to say that the Persian Gulf