About a century before Pizarro landed, Tupac Yupanqui, the greatest of the Inca conquerors, crossed the rough mountains, bleak plateaux, and waterless deserts which lie between the habitable part of Bolivia and the irrigable valleys of northern Chile, and rapidly overran the coast for six hundred miles. As one goes south the plain broadens, the short rivers flowing from the mountains grow larger, the rainfall and the area available for cultivation increase, and from Santiago a wide valley, the heart of Chile, stretches between the Andes and the coast range, sustaining a dense population. As far south as the river Maule, the limit of Tupac's conquests, irrigation is necessary for crops. In all these valleys dwelt various tribes whose system of agriculture and civilisation was similar to that of the Incas. Only the southern peoples inhabiting the rainy and forested regions beyond the Maule refused to submit. Huaina Capac, Tupac's son, was once obliged to undertake a campaign to consolidate the Inca power, but Chile north of the Maule became thoroughly attached to the Cuzco dynasty. Little resistance was encountered when Almagro invaded this country just after Pizarro's entry into the Peruvian capital. He advanced as far as the Maule, finding everywhere a population probably as dense as that of the present day. Agriculture was highly developed; the people were clothed in substantial stuffs of their own manufacture; they mined copper, tin, and lead, and possessed excellent arms and tools. The tribes all spoke the same language, but each enjoyed a degree of autonomy under its own chiefs. Their habits were democratic; they loved freedom and independence; the Inca socialistic system did not prevail; and each farmer owned his own field and could transmit it to his children. The race was large and vigorous, the selected survivors from among immigrants who had been greatly improved by countless generations of struggle in the more rigorous climate. As one approached the cold and rainy mountains of southern Chile their characteristics became more pronounced and south of the Maule warlike, half-savage tribes proudly maintained their independence. Almagro's sole pre-occupation was gold, but he vainly searched the valleys as far as the southern boundary of the Inca empire. Here he encountered serious resistance from the independent tribes, and though victorious in his fights, concluded that it was not worth while remaining in such a cold and goldless country. He abandoned Chile and returned to Peru, there to meet his death at Pizarro's hands. [Illustration: BRIDGE ON THE ROAD BETWEEN SANTIAGO AND MENDOZA.]