Though agriculture is regarded with contempt and aversion by pastoral nomads and is resorted to for a livelihood only when they lose their herds by a pest or robbery, or find their pasture lands seriously curtailed, nevertheless nomadism yields such a precarious and monotonous subsistence that it is not infrequently combined with a primitive, shifting tillage.  The Kalmucks of the Russian steppes employ men to harvest hay for the winter feeding.  The Nogai Tartars practice a little haphazard tillage on the alluvial hem of the steppe streams.[1116] Certain Arab tribes living east of the Atbara and Gash Rivers resort with their herds during the dry season to the fruitful region of Cassala, which is inundated by the drainage streams from Abyssinia, and there they cultivate dourra and other grains.[1117] The Bechuana tribes inhabiting the rich, streamless grassland of the so-called Kalahari Desert rear small herds of goats and cultivate melons and pumpkins; among the other Bechuana tribes on the eastern margin of the desert, the men hunt, herd the cattle and milk the cows, while the women raise dourra, maize, pumpkins, melons, cucumbers and beans.[1118] [Compare maps pages 105, 487.]

Such supplementary agriculture usually shifts with the nomad group.  But where high mountains border rainless tracts, their piedmont districts regularly develop permanent cultivation.  Here periodic rains or melting snows on the ranges fill the drainage streams, whose inundation often converts their alluvial banks into ready-made fields.  The reliability of the water supply anchors here the winter villages of the nomads, which become centers of a limited agriculture, while the pasture lands beyond the irrigated strips support his flocks and herds.  Where the piedmont of the Kuen Lun Mountains draws a zone of vegetation around the southern rim of the Takla Makan Desert, Mongol shepherds raise some wheat, maize and melons as an adjunct to their cattle and sheep; but their tillage is often rendered intermittent by the salinity of the irrigating streams.[1119] Along the base of the Tian Shan Mountains, the felt yurt of the Gobi nomad gives place to Turki houses with wheat and rice fields, and orchards of various fruits; so that the whole piedmont highway from Hami to Yarkand presents an alternation of desert and oasis settlement.[1120] Even the heart of arid Arabia shows fertile oases under cultivation where the lofty Nejd Plateau, with its rain-gathering peaks over five thousand feet high, varies its wide pastures with well tilled valleys abounding in grain fields and date-palm groves.[1121] Along the whole Saharan slope of the Atlas piedmont a series of parallel wadis and, farther out in the desert, a zone of artesian wells, sunk to the underground bed of hidden drainage streams from the same range, form oases which are the seat of permanent agriculture and more or less settled populations.  The Saharan highlands of Tibesti, whose mountains rise to 8,300 feet, condense a little rain and permit the Tibbus to raise some grain and dates in the narrow valleys.[1122]