📖 Quick review
People likely crossed a land bridge between Asia and North America, called Beringia, searching for food. When glaciers melted, water covered Beringia and the Bering Strait formed, so later settlers arrived by boat. As settlers moved south, they populated both North and South America and developed unique cultures. Around ten thousand years ago, humans began domesticating plants and animals, leading to agriculture, more reliable food, population growth, and permanent settlements. In Mesoamerica, the Olmec created a written language, built aqueducts, and influenced later cultures such as the Maya and Aztec. The Maya perfected calendar and written systems but declined after poor soil and a drought lasting nearly two centuries. The Aztec built Tenochtitlán with aqueducts, markets, and causeways, practiced daily ritual sacrifice, and used chinampas for farming. The Inca Empire spanned the Andes, used stepped roads and the chasquis relay for communication, and kept records with quipu.