The document provides a brief history of Mexico through several sections. It describes how scientists can trace human history through DNA. It then discusses a major climatic event in A.D. 535 that caused crop failures and floods. The Columbian Exchange introduced American foods like corn and potatoes, helping diminish disease. Mexico City has a population of 20 million but half live in poverty dealing with traffic, infrastructure and crime problems. The document examines Mexico's multicultural past and the experiences of Mexican immigrants risking their lives to cross into the United States for better opportunities and to achieve their goals, as described in the book and film cited.