Every June, after the rainy season ends in the grassy highlands of southern Peru, the residents of four villages near Huinchiri, at more than 12,000 feet in altitude, come together for a three-day festival. Men, women and children have already spent days in busy preparation: They’ve gathered bushels of long grasses, which they’ve then soaked, pounded, and dried in the sun. These tough fibers have been twisted and braided into narrow cords, which in turn have been woven together to form six heavy cables, each the circumference of a man’s thigh and more than 100 feet long.