Centuries ago, waves of Han emigrants fled south to avoid natural disasters and social unrest in northern China. They settled in the mountains of Fujian and parts of Jiangxi and Guangdong provinces. They called themselves "Kejia,” or guests, and built fortress-like tulou for protection. Within their sturdy walls, the people became self-sufficient and somewhat isolated. If enemies come, the tulou will be strong fortress once the gate is locked. A tulou can accommodate as many as 200 to 800 people. [Photo/CFP]