Secured from want by this intelligent socialism, their lives and rights safe under laws administered with inflexible severity, bound closely by family and governmental ties, trained from childhood in industry and obedience, the Incas seemed destined to dominate and absorb the more loosely organised tribes with whom they came in contact, provided that they did not become inert, stationary, and unwarlike, and cease to produce individuals possessing initiative. The dynamic elements indispensable to expansion were furnished by the ruling clan and by fanaticism. The offspring of Manco Capac partook of his divinity and each emperor left numerous sons, whose descendants constituted a privileged class. In the process of time there gathered around the emperor thousands of men of his own kindred, devoted from their birth to warfare and statecraft.
[Illustration: ANCIENT PERUVIAN MONUMENT.]
Under the fourth emperor the Incas were successful in a life and death struggle against a tribe with whom they had hitherto shared the valley that surrounds Cuzco. Under the two succeeding emperors they extended their dominions south to the transverse range of mountains which separates the Peruvian from the Titicacan plateau. Yahuar Huaccac, the seventh sovereign, conquered the tribes on the eastern slopes, and by the beginning of the fourteenth century the Inca domain included the southern third of the great valley of Peru--an area of fifteen thousand square miles, containing probably two millions of people. Uira Cocha, the eighth emperor, began that wonderful series of conquests which within a century and a half extended over half of South America. On the other side of the Vilcañota "nudo" lay the vast basin which takes its name from Lake Titicaca. Too high and too cold for cereals, the plateau was inhabited by tribes of shepherds, who made no prolonged resistance when attacked by the armies of the Inca. Their rapid and complete incorporation into the Inca system followed. Colonies swarmed from the over-populated provinces of old Peru into the newly acquired territories. The Titicacan copper mines furnished the material for weapons and tools, and a great commerce in exchanging the wool, potatoes, and livestock of the higher regions for the maize and cotton of the lower added to the prosperity of the whole empire. This conquest doubled the extent of the Inca domain and opened up a vast field for colonising expansion within their own territory. Once achieved, the nation turned its attention to the conquest of the North. Beyond the gorge of the Apurimac--the Inca boundary in that direction--lay the rival nation of the Chancas, a vigorous and expanding people who were at the head of a great confederation of tribes which covered the northern two-thirds of the central plateau of Peru, and probably also included the Quichua-speaking tribes of the coast.