As is true of all countries, Korea's geography was a major factor in shaping its history geography also influenced the manner in which the inhabitants of the peninsula emerged as a people sharing the common feeling of being Koreans (see Physical Environment , ch. 2). The Korean Peninsula protrudes southward from the northeastern corner of the Asian continent and is surrounded on three sides by large expanses of water. Although Japan is not far from the southern tip of this landmass, in ancient times events on the peninsula were affected far more by the civilizations and political developments on the contiguous Asian continent than by those in Japan (see fig. 1).

Because the Yalu and Tumen rivers have long been recognized as the border between Korea and China, it is easy to assume that these rivers have always constituted Korea's northern limits. But such was not the case in the ancient period. Neither of the rivers was considered to be sacrosanct by the ancient tribes that dotted the plains of Manchuria and the Korean Peninsula. Because the rivers freeze in the winter, large armies were able to traverse them with ease. Even when the rivers were not frozen, armies equipped with iron tools could easily build ships to cross them.

The Korean people trace their origins to the founding of the state of Choson. Choson rose on the banks of the Taedong River in the northwestern corner of the peninsula and prospered as a civilization possessing a code of law and a bronze culture. The Choson people gradually extended their influence not only over other tribes in the vicinity, but also to the north, conquering most of the Liaodong Basin. However, the rising power of the feudal state of Yen in northern China (1122-225 B.C.) not only checked Choson's growth, but eventually pushed it back to the territory south of the Ch'ongch'on River, located midway between the Yalu and Taedong rivers. The Chinese had discovered iron by this time and used it extensively in farming and warfare the Choson people were not able to match them. Yen became established in the territory vacated by Choson.

Meanwhile, much of what subsequently came to constitute China proper had been unified for the first time under Qin Shi Huangdi. Subsequently, Yen fell to the Qin state the Qin Dynasty (221-207 B.C.) was in turn replaced by a new dynasty, the Han (206 B.C.- A.D. 220). In 195 B.C. a former officer of Yen took over the throne of Choson by trickery, after which he and his descendants ruled the kingdom for eighty years but in 109-108 B.C. China attacked Choson and destroyed it as a political entity. The Han Chinese then ruled the territory north of the Han River as the Four Eastern Districts the original territory of Choson became Lolang (or Nangnang in Korean). (North Korean historians have argued that the Lolang District was located more to the northwest of the Korean Peninsula, perhaps near Beijing. This theory, however, has not been universally accepted.) Until the Han period the Korean Peninsul2d6 ula had been a veritable Chinese colony. During some 400 years, Lolang, the core of the colony, had become a great center of Chinese art, philosophy, industry, and commerce. Many Chinese immigrated into the area the influence of China 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.

Data as of June 1990