Transcription: By the early 1400s, the Inca of Peru had created an empire that stretched roughly 3,000 miles through the Andes Mountains of South America. To grow crops in the steep, rugged terrain, they cut into the slopes to create terraces. They were also master builders who could fit stones securely together without cement or mortar. To rule their vast empire, the Inca developed an efficient system of communication. Teams of runners relayed messages along mountain paths covering hundreds of miles a day. They carried khipus, slender ropes with knotted colored strings representing information too detailed ...
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