Though the conquering propensities of nomadic tribes make large families desirable, in order to increase the military strength of the horde, and though shepherd folk acquiring new and rich pastures develop patriarchal families, as did the Jews after the conquest of Canaan, nevertheless the limited water and food supply of desert and grassland, as well as the relatively low-grade economy of pastoral life, impose an iron-bound restriction upon population, so that as a matter of fact patriarchal families are rare.  When natural increase finds no vent in emigration and dispersal, marriage among nomads becomes less fruitful.[1141] Artificial limitation of population occurs frequently among desert-dwellers.  In the Libyan oasis of Farafeah, the inhabitants never exceed eighty males, a limit fixed by a certain Sheik Murzuk.[1142] Poverty of food supply explains the small number of children in the typical Turkoman family.  Among the Koko-Nor Tibetans, monogamy is the rule, polygamy the exception and confined to the few rich, while families never include more than two or three children.[1143] According to Burckhardt, three children constitute a large family among the Bedouins, much to the regret of the Bedouins themselves.  Mohammedans though they are, few practice polygamy, while polyandry and female infanticide existed in heathen times.[1144] Desert peoples seem to be naturally monogamous.[1145]

[Sidenote:  Trade of nomads.]

The prevailing poverty, monotony and unreliability of subsistence in desert and steppe, as well as the low industrial status, necessitate trade with bordering agricultural lands.  The Bedouins of Arabia buy flour, barley for horse feed, coffee and clothing, paying for them largely with butter and male colts.  The northern tribes resort every year to the confines of Syria, when they are visited by pedlers from Damascus and Aleppo.[1146] The tribes from Hasa and the Nejd pasture land bring horses, cattle and sheep to the city of Koweit at the head of the Persian Gulf to barter for dates, clothing and firearms; and large encampments of them are always to be seen near this town.[1147] Arabia and the Desert of Kedar sold lambs, rams and goats to the markets of ancient Tyre.[1148] The pastoral tribes of ancient Judea in times of scarcity went to Egypt for grain, which they purchased either with money or cattle.  The picture of Jacob’s sons returning from Egypt to Canaan with their long lines of asses laden with sacks of corn is typical for pastoral nomads; so is their ultimate settlement, owing to protracted famine, in the delta land of Goshen.  The Kirghis of the Russian and Asiatic steppes barter horses and sheep for cereals, fine articles of clothing, and coarse wooden utensils in the cities of Bukhara and the border districts of Russia.  Occasionally the land of the nomad yields other products than those of the flocks and herds, which enter therefore into their trade.  Such is the salt of the Sahara, secured at Taudeni and Bilma, the gums of the Indus desert, and balm of Gilead from the dry plateau east of Jordan.