It is scarcely too much to say that the possession of Ashdod, Tyre, and Carchemish, involved the lordship of Syria, which could not be permanently retained except by the occupation of those cities.
The countries by which the Babylonian Empire was bounded were Persia on the east, Media and her dependencies on the north, Arabia on the south, and Egypt at the extreme southwest.

Directly to the west she had no neighbor, her territory being on that side washed by the Mediterranean.
Of Persia, which must be described at length in the next volume, since it was the seat of Empire during the Fifth Monarchy, no more need be said here than that it was for the most part a rugged and sterile country, apt to produce a brave and hardy race, but incapable of sustaining a large population.

A strong barrier separated it from the great Mesopotamian lowland; and the Babylonians, by occupying a few easily defensible passes, could readily prevent a Persian army from debouching on their fertile plains.

On the other hand, the natural strength of the region is so great that in the hands of brave and active men its defence is easy; and the Babylonians were not likely, if an aggressive spirit led to their pressing eastward, to make any serious impression in this quarter, or ever greatly to advance their frontier.
To Media, the power which bordered her upon the north, Babylonia, on the contrary, lay wholly open.

The Medes, possessing Assyria and Armenia, with the Upper Tigris valley, and probably the Mons Masius, could at any time, with the greatest ease, have marched armies into the low country, and resumed the contest in which Assyria was engaged for so many hundred years with the great people of the south.