The fourth-largest country by area in the world—just after the United States and before Brazil—China is a land of complex cultures and climates. It shares its border with 15 countries, and its territory stretches from the tropical south (at the crossing into Laos) to the subarctic north (where it juts into Siberia).

Within that sprawling land mass live 1.43 billion people, which is more than a sixth of the planet’s total. But population density runs at extremes from west to east. The World Factbook notes that an “overwhelming majority … is found in the eastern half of the country.” Six Chinese cities are home to more than 10 million people: the populations of Shenzhen, Tianjin, Guangdong, Chongqing, Beijing, and Shanghai number 11.9, 13.2, 12.7, 14.8, 19.6, and 25.6 million, respectively.