China is the worlds oldest continuous civilization, with a history characterized by repeated divisions and reunifications amid alternating periods of peace and war, and violent dynastic change. Power was generally concentrated in the hands of the emperor, but sometimes shifted to powerful officials, regional warlords, imperial relatives, and eunuchs. The countrys population of over 1.3 billion people makes up a fifth of the worlds population and is overwhelmingly of the Han Chinese ethnicity. Their language, Chinese, is divided into many spoken variations. These spoken languages are used today in modern society and in many parts of Europe and America.