From time to time streams of migration swept into Palestine and Syria. Semitic tribes wandered northwards from their home in Arabia to seek sustenance in its more fertile fields, to plunder, or to escape the pressure of tribes in the rear. The course leads naturally into either Palestine or Babylonia, and, following the Euphrates, northern Syria is eventually reached. Tribes also moved down from the north: nomads, or offshoots from the powerful states which stretch into Asia Minor. Such frequently recurring movements introduced new blood. Tribes, chiefly of pastoral habits, settled down among others who were so nearly of their own type that a complete amalgamation could be effected, and this without any marked modification of the general characteristics of the earlier inhabitants. It is from such a fusion as this that the ancestors of the Jews were descended, and both the history and the genius of this people can be properly understood only by taking into account the physical features of their land and the characteristics of the Semitic races in general (see PALESTINE, SEMITIC LANGUAGES). 2. _Society and Religion._--The similarity uniting the peoples of the East in respect of racial and social characteristics is accompanied by a striking similarity of mental outlook which has survived to modern times. Palestine, in spite of the numerous vicissitudes to which it has been subjected, has not lost its fundamental characteristics. The political changes involved in the Babylonian, Assyrian, Egyptian or Persian conquests surely affected it as little as the subsequent waves of Greek, Roman and other European invasions. Even during the temporary Hellenization in the second great period the character of the people as a whole was untouched by the various external influences which produced so great an effect on the upper classes. When the foreign civilization perished, the old culture once more came to the surface. Hence it is possible, by a comprehensive comparative study of Eastern peoples, in both ancient and modern times, to supplement and illustrate within certain limits our direct knowledge of the early Jewish people, and thus to understand more clearly those characteristics which were peculiar to them, in relation to those which they shared with other Oriental peoples.