The search for better land, milder

The search for better land, milder climate, and easier conditions of living starts many a movement of peoples which.in view of their purpose, necessarily leads them into an environment sharply contrasted to their original habitat. Suchhas been the radial outflow of the Mongoloid tribes downfrom the rugged highlands of central Asia to the fertile riverlowlands of the peripheral lands; the descent of the Iran pastors upon the agricultural folk of the Indus, Ganges andMesopotamian valleys, and the swoop of desert-born conquerors upon the unresisting tillers of well-watered fields in alltines, from the ancient Hyksos of the Nile to the modernfulbe of the Niger Valley.