The Lelang Commandery was a commandery of the Han dynasty established after it had conquered Wiman Joseon in 108 BC and lasted until Goguryeo conquered it in 313. The Lelang Commandery extended the rule of the Four Commanderies of Han as far south as the Han River in present-day South Korea. South Korean scholars have described its administrative areas as being limited to the Pyongan and Hwanghae regions, whose southern bounds lie roughly 75 miles north of the Han River.

The Han dynasty was an imperial dynasty of China, established by Liu Bang and ruled by the House of Liu. The dynasty was preceded by the short-lived Qin dynasty (221–206 BC) and a warring interregnum known as the Chu–Han contention (206–202 BC), and it was succeeded by the Three Kingdoms period (220–280 AD). The dynasty was briefly interrupted by the Xin dynasty (9–23 AD) established by the usurping regent Wang Mang, and is thus separated into two periods—the Western Han and the Eastern Han (25–220 AD). Spanning over four centuries, the Han dynasty is considered a golden age in Chinese history, and had a permanent impact on Chinese identity in later periods. The majority ethnic group of modern China refer to themselves as the "Han people" or "Han Chinese". The spoken Sinitic language and written Chinese are referred to respectively as the "Han language" and "Han characters".