The dynasty founded by Manco-Ccapac at Cuzco is generally believed to have dated from the twelfth century. All the genealogies furnished by historians are more or less incomplete, limiting to thirteen or fourteen, at most, the number of monarchs who reigned during that long period of four hundred years. The list of Incas given by Garcilaso de la Vega, and regarded as the most reliable, contains the names of thirteen Princes of the Sun. Most of the authorities of importance name Manco-Ccapac as the founder of the Empire of the Incas, with Mama Ocllo as Coya, or Empress; though opinion is greatly divided as to their origin and the date of their imperial accession. One well-known historian of the Conquest, Montesinos, places the period of the first appearance of this royal line in the sixth century after the Deluge. It is related that, during that remote age, there arrived in Cuzco a family of four couples who civilized this region. The eldest of the four brothers, having gained possession of the territory, divided it into four portions, or _suyos_, from which it took the name of Tahuantinsuyo, “the kingdom of the four regions.” The territory to the south was called Collasuyo, to the west Cuntisuyo, to the north Chinchasuyo, and to the east Antisuyo. The youngest brother afterward secured command of the kingdom and became the first of a line of princes who governed Peru up to the time of the Spanish Conquest. The most interesting feature of this tradition is the division of the rule of these monarchs into three great dynasties, of which the first was that of the Pirhuas (from _pyru_, meaning “fire,” apparently indicating that they were fire-worshippers), the second, that of the Amauttas, or wise men, and the third the Inca dynasty. The first of the Pirhuas founded the city of Cuzco in the name of Viracocha, “the Supreme Being,” and one of his successors built a great temple in Cuzco (perhaps Sacsahuaman, which is believed to antedate the Inca period), while another ruler of the same royal line is credited with having reformed the calendar, built public roads and established severe rules in religion. One of these kings, the record says, “died while repressing an invasion of depraved people from the plains.” The Amauttas made many wise laws, reformed the calendar and the religion of Viracocha, organized the military forces of the kingdom and repelled the Chimus of the plains. During the reign of the last of the Amauttas, we are told, “was fulfilled the fourth sun of the Amauttas, and there took place a great invasion of ferocious tribes who attacked the kingdom in different parts, obliging the sovereigns of Cuzco to flee to the grottos of Tamputoko for four hundred years, during which they lost their literature and a great part of the Amautta culture; the advent of the Incaic dynasty restored the power of the royal line, and made Cuzco again the centre of a great and beneficent civilization.” In the light of modern research, which is continually