The first countries assailed were the Oriental possessions of the
Byzantine Empire. In the reign of Abu-beker, Syria and Mesopotamia were
subdued by Arabian armies. Under the next caliph, Omar, Egypt was
conquered and Northern Africa overrun. The Arabs, or Saracens, as they
were also called, met with comparatively little resistance in the
Oriental countries, the countries beyond Mount Taurus; and this may be
accounted for by the fact that these were the parts of the Roman Empire
in which both Roman law and Christianity had taken least hold.
Thus the Eastern Empire was shorn of all its Oriental possessions; and
even the farther East--Persia and the lands beyond, to India--was added
to the Moslem dominion.