The earliest known ruler of the Han dynasty in China, overseeing significant territorial expansion, was Emperor Gaozu, also known as Liu Bang. He established the dynasty in 206 BC after defeating the Qin Dynasty's forces and initiated a period of stability, known as the Western Han, which lasted for over four centuries. Emperor Gaozu's reign emphasized consolidation of power, economic reforms, and expansion of trade along the Silk Road, contributing to the prosperity of early imperial China.