up these stages, as part of the story of geographical discovery.

Regarded from the point of view of geography, this spread of man's
knowledge might be compared to the growth of a huge oyster-shell,
and, from that point of view, we have to take the north of the
Persian Gulf as the apex of the shell, and begin with the Babylonian
Empire. We first have the kingdom of Babylon--which, in the early
stages, might be best termed Chaldæa--in the south of Mesopotamia
(or the valley between the two rivers, Tigris and Euphrates), which,
during the third and second millennia before our era, spread along
the valley of the Tigris. But in the fourteenth century B.C., the
Assyrians to the north of it, though previously dependent upon
Babylon, conquered it, and, after various vicissitudes, established
themselves throughout the whole of Mesopotamia and much of the
surrounding lands. In 604 B.C. the capital of this great empire was
moved once more to Babylon, so that in the last stage, as well as in
the first, it may be called Babylonia. For purposes of distinction,
however, it will be as well to call these three successive stages
Chaldæa, Assyria, and Babylonia.

Meanwhile, immediately to the east, a somewhat similar process
had been gone through, though here the development was from north
to south, the Medes of the north developing a powerful empire in
the north of Persia, which ultimately fell into the hands of Cyrus
the Great in 546 B.C. He then proceeded to conquer the kingdom of
Lydia, in the northwest part of Asia Minor, which had previously
inherited the dominions of the Hittites. Finally he proceeded to
seize the empire of Babylonia, by his successful attack on the
capital, 538 B.C. He extended his rule nearly as far as India on
one side, and, as we know from the Bible, to the borders of Egypt