North and South America offered over most of their area conditions of climate and soil highly favorable to agriculture, and a fair list of indigenous cereals, tubers, and pulses yielding goodly crops even to superficial tillage. Maize especially was admirably suited for a race of semi-migratory hunters. It could be sown without plowing, ripened in a warm season even in ninety days, could be harvested without a sickle and at the pleasure of the cultivator, and needed no preparation beyond roasting before it was ready for food.[121] The beans and pumpkins which the Indians raised also needed only a short season. Hence many Indian tribes, while showing no trace of pastoral development, combined with the chase a semi-nomadic agriculture; and in a few districts where geographic conditions had applied peculiar pressure, they had accomplished the transition to sedentary agriculture. [Sidenote: Land per capita under various cultural and geographic conditions.] Every advance to a higher state of civilization has meant a progressive decrease in the amount of land necessary for the support of the individual, and a progressive increase in the relations between man and his habitat. The stage of social development remaining the same, the per capita amount of land decreases also from poorer to better endowed geographical districts, and with every invention which brings into use some natural resource. The following classification[122] illustrates the relation of density of population to various geographic and socio-economic conditions. Hunter tribes on the outskirts of the habitable area, as in Arctic America and Siberia, require from 70 to 200 square miles per capita; in arid lands, like the Kalahari Desert and Patagonia, 40 to 200 square miles per capita; in choice districts and combining with the chase some primitive agriculture, as did the Cherokee, Shawnee and Iroquois Indians, the Dyaks of Borneo and the Papuans of New Guinea, 1/2 to 2 square miles per capita. Pastoral nomads show a density of from 2 to 5 to the square mile; practicing some agriculture, as in Kordofan and Sennar districts of eastern Sudan, 10 to 15 to the square mile. Agriculture, undeveloped but combined with some trade and industry as in Equatorial Africa, Borneo and most of the Central American states, supports 5 to 15 to the square mile; practised with European methods in young or colonial lands, as in Arkansas, Texas, Minnesota, Hawaii, Canada and Argentine, or in European lands with unfavorable climate, up to 25 to the square mile. Pure agricultural lands of central Europe support 100 to the square mile, and those of southern Europe, 200; when combining some industry, from 250 to 300. But these figures rise to 500 or more in lowland India and China. Industrial districts of modern Europe, such as England, Belgium, Saxony, Departments Nord and Rhone in France, show a density of 500 to 800 to the square mile. [See maps pages 8 and 9.]