While this was occurring on the Korean peninsula, much of what subsequently became China proper was unified for the first time under Qin Shi Huangdi. Subsequently, Yen fell to the Qin state. The Qin Dynasty (221-207 BC) was later replaced by the Han Dynasty (206 BC-220 AD). In 195 BC, a former Yen officer took over the Gojoseon throne by trickery, which he and his descendants ruled for eighty years.
In 109-108 BC, the Han attacked Gojoseon and destroyed it as a political entity. The Han then ruled the territory north of the Han River known as the Four Eastern Districts. The original territory of Gojoseon became Lolang (or Nangnang in Korean), a Chinese colony. During some 400 years, Lolang, the core of the colony, had become a great center of Chinese art, philosophy, industry, and commerce. The Chinese colonists were not known for oppression, they were content to exercise a small degree of control while allowing the Korean people considerable political freedom. Many Chinese immigrated into the area and Chinese influence extended beyond the territory it administered. The tribal states south of the Han River paid tribute to the Chinese and patterned much of their civilization and government after Chinese models.
The territory south of the Han River is relatively distant from the Asian continent; hence, the people living there were initially able to develop independently, without much involvement with events on the continent. The early settlers of this region gradually organized themselves into some seventy clan states that were in turn grouped into three tribal confederations known as Chinhan, Mahan, and Pyonhan. Chinhan was situated in the middle part of the peninsula, Mahan in the southwest, and Pyonhan in the southeast. Their economies were predominantly agricultural, and their level of development was such that they built reservoirs and irrigation facilities. These tribal states began to be affected by what was happening in the region north of the Han River around the first century BC.