y wars of conquest, and
systems of intercommunication and transportation. The Babylonian,
Assyrian, Persian, Alexandrian, and Roman empires are striking examples
of the diffusion of knowledge and the spread of ideas over different
geographical boundaries and through tribal and national organizations;
and, indeed, the contact of the barbarian hordes with improved systems
of culture was but a process of interchange and intermingling of
qualities of strength and vigor with the conventionalized forms of
human society.

One of the most remarkable movements was that of the rise and expansion
of the Arabian Empire, which was centred about religious ideals of
Mohammed and the Koran. Having accepted the idea of one God universal,
which had been so strongly emphasized by the Hebrews, and having
accepted in part the doctrine of the teachings of Jesus regarding the
brotherhood of man, Mohammed was able through the mysticism of his
teaching, in the Koran, to excite his followers to a wild fanaticism.
Nor did his successors hesitate to use force, for most of their
conquests were accomplished by the power of the sword. At any rate,
nation after nation was forced to bow to Mohammedanism and the Koran,
in a spectacular whirlwind of conquest such as the world had not
previously known.

It is remarkable that after the decline of the old Semitic
civilization, as exhibited in the Babylonian and Assyrian empires, the
practical extinction of the Phoenicians, the conquest of Jerusalem, and
the spread of the Jews over the whole world, there should have risen a
new Semitic movement to disrupt {305} and disorganize the world. It is
interesting to note in this connection, also, that wherever the Arabs
went they came in contact with learned Jews of high mentality, who
co-operated with them in advancing learning.

_The Rise and Expansion of the Arabian Empire_.--Mohammedanism, which
arose in the beginning of the seventh century, spread rapidly over the
East and through northern Africa, and extended into Spain. All Arabia
was converted to the Koran, and Persia and Egypt soon after came under
its influence. In the period 623-640, Syria was conquered by the
Mohammedans, upper Asia in 707, and Spain in 711. They established a
great caliphate, extending from beyond the Euphrates through Egypt and
northern Africa to the Pyrenees in Spain. They burned the great
library at Alexandria, founded by Ptolemy, destroying the manuscripts
and books in a