while they precluded Syria herself from attaining national unity, always
tended to protect her separate provinces, or "kingdoms," from the
full effects of foreign aggression. One city-state could be traversed,
devastated, or annexed, without in the least degree affecting
neighbouring areas. It is true that the population of Syria has always
been predominantly Semitic, for she was on the fringe of the great
breeding-ground of the Semitic race and her landward boundary was open
to the Arabian nomad. Indeed, in the whole course of her history the
only race that bade fair at one time to oust the Semite in Syria was the
Greek. But the Greeks remained within the cities which they founded or
rebuilt, and, as Robertson Smith pointed out, the death-rate in Eastern
cities habitually exceeds the birth-rate; the urban population must be
reinforced from the country if it is to be maintained, so that the type
of population is ultimately determined by the blood of the peasantry.(1)
Hence after the Arab conquest the Greek elements in Syria and Palestine
tended rapidly to disappear. The Moslem invasion was only the last of a
series of similar great inroads, which have followed one another since
the dawn of history, and during all that time absorption was continually
taking place from desert tribes that ranged the Syrian border. As we
have seen, the country of his adoption was such as to encourage
the Semitic nomad's particularism, which was inherent in his tribal
organization. Thus the predominance of a single racial element in the
population of Palestine and Syria did little to break down or overstep
the natural barriers and lines of cleavage.

(1) See Robertson Smith, _Religion of the Semites_, p. 12
f.; and cf. Smith, _Hist. Geogr._, p. 10 f.

These facts suffice to show why the influence of both Egypt and Babylon
upon the various peoples and kingdoms of Palestine was only intensified