Subtitles section Play video Print subtitles It was the Western Hemisphere's largest empire ever, with a population of nearly 10 million subjects. Over an area of more than 900,000 square kilometers, its people built massive administrative centers, temples, and extensive road and canal systems. They did so in an inhospitable, extreme terrain, all without the use of wheels, horses, iron, or even written language. Yet within 100 years of its rise in the fifteenth century, the Inca Empire would be no more. According to legend, the ancestors of the Inca rulers were created by the sun god Inti, and they emerged from a cave called Tambo Toco. Leading four brothers and four sisters was Ayar Manco, who carried a golden staff with instructions to find the place where it would sink into the ground, showing fertile soil. After many adventures and extensive searching, Ayar Manco and his siblings reached the Cuzco Valley, where the staff pierced the ground. After fighting off the fierce local native population, they founded their capital, and Ayar Manco became Manco Capac, the first Sapa Inca, or king of the Incas. Archaeological evidence suggests that the Incas first settled in this valley around 1200 CE. They remained a small kingdom until 1438, when they were nearly overrun by the neighboring Chanka tribe. The Inca king at this time, Viracocha, and his designated heir fled in fear, but one of his other sons remained and successfully rallied the city's defenses. For his military skill, he became the ninth Inca ruler, assuming the name of Pachacuti, or "Cataclysm." Pachacuti expanded Inca rule throughout the Andes mountains, transforming the kingdom into an empire through extensive reforms. The empire's territory was reorganized as Tahuantinsuyu, or "four quarters," with four divisions ruled by governors reporting to the king. Although the Inca had no writing, they used a complex system of knotted strings called quipu to record numbers and perhaps other information. A decimal-based bureaucracy enabled systematic and efficient taxation of the empire's subjects. In return, the empire provided security, infrastructure, and sustenance, with great storehouses containing necessities to be used when needed. Great terraces and irrigation works were built and various crops were grown in at different altitudes to be transported all over the empire. And it was during Pachacuti's reign that the famous estate of Machu Picchu was constructed. Pachacuti's son Topa Inca continued the empire's military expansion, and he eventually became ruler in 1471 CE. By the end of his reign, the empire covered much of western South America. Topa's son Huayna Capac succeeded him in 1493. But the new ruler's distant military campaigns strained the social fabric. And in 1524, Huayna Capac was stricken by fever. Spanish conquistadors had arrived in the Caribbean some time before, bringing diseases to which the native peoples had no resistance. Millions died in the outbreak, including Huayna Capac and his designated heir. The vacant throne ignited a civil war between two of the surviving brothers, Atahualpa and Huascar, greatly weakening the empire. In 1532, after finally winning the Inca civil war, Atahualpa and his army encountered the European invaders. Although greatly outnumbered, Francisco Pizarro and his small group of conquistadors stunned the king's much larger force with guns and horses, neither of which they had seen before. Atahualpa was taken captive and killed about a year later. The Spanish conquerors were awed by the capital of Cuzco. Pizarro described it as so beautiful that “it would be remarkable even in Spain.” Though the capital had fallen and the native population had been destroyed by civil war and disease, some Incas fell back to a new capital at Vilcabamba and resisted for the next 40 years. But by 1572, the Spaniards had destroyed all remaining resistance along with much of the Incas' physical and cultural legacy. Thus, the great Inca empire fell even faster than it had risen.