While Europe and Asia were crushed by the Black Death in the Americas, isolation not only protected civilizations, but helped them prosper. But this world was devoid of horses, iron tools, and wheels. But intensive agriculture was practiced on the steep slopes and at the foot of the Andes with wooden tools, producing vegetables not found in Europe: potatoes, pumpkins, beans, tomatoes and corn and growing llamas and alpacas. The Incas [71] built bridges, roads and cities in high mountain areas. The royal dignitaries supervised the cities and made sure that the workshops of pottery, textiles and decorative metal objects worked efficiently. The king or Sapa Inca ruled the country of Cuzco . The Incas did not know how to write, they kept everything to rememberquipu - strings with knots that represented information regarding the population or taxes. Somewhere in the Andes Mountains of Central America, in 1438 , a young Inca ruler (Sapa Inca) named Pachacuti believed that he was descended from Inti, the sun god, who had given him the right to rule. He was worshiped like the gods. When the rival Chankas tribe of Peru invaded Cuzco, while his father and brother fled the scene, Pachacuti gathered his army and prepared for a desperate defense of his homeland. In battle, Chankas brought the skulls of their enemies and the mummy of their dead king. They were defeated so that the legend says that even the stones were raised to fight on Pachacuti's side. In reality, the Inca soldiers used bolas-stones slings tied with leather straps, wooden spears and star-shaped heads. He decided to expand his empire. In 1450 , he conquered the Titicaca basin , and in 1463 he started a war against the lupaca and colla tribes. Under the command of Topa, son of Pachacuti, the Inca army defeated the neighboring empire Chimu in 1466 , and Topa continued to expand after becoming Sapa Inca in 1471 . In 15 years, he conquered the distant southern lands, later dominating the northern and western territories. Huyana Capac expanded the empire and built a second capital in Quito. In 1525, the empire stretched for 3,000 km along western South America. In the same year, the empire was divided between his sons, Huascar who took the south, and Atahulpa who took the north. The division led to civil war, and in 1532-1535, taking advantage of their conflict, the Spaniards conquered and destroyed the empire. The most important remnant of the empire is Machu Picchu , a city perched on a mountain top and camouflaged so well that it was discovered in 1911. It was one of the last bastions to defend the Incas against the Spanish invaders. Built of precision-joined stones without mortar, Machu Picchu was a spiritual center with an astronomical observatory and temples.
