During the first millennium B.C., bronze technology and then iron technology are introduced into the Korean peninsula, probably from the northern regions of the continental mainland, and are used to produce both utilitarian and ritual implements. Advances in metallurgy and a dependence on agriculture spur the development of a more complex social hierarchy, which is attested by increasingly elaborate burial practices. The migration of different populations into the peninsula from neighboring regions in Manchuria and Siberia during the Bronze Age also leads to regional variations in the material, form, and function of ceramic wares, including the appearance of painted wares. Ceramics of the Iron Age take even more diverse forms with the introduction of the potter's wheel.
The first wall-towned states are formed on the peninsula during this period. The oldest and most advanced is Old Chosôn, situated in the basins of the Liao and Taedong rivers, just southeast of present-day Manchuria. At the end of the second century B.C., China's Han dynasty (206 B.C.220 A.D.), after conquering Wiman Chosôn (the successor state to Old Chosôn), establishes the first Chinese military commandaries on the Korean peninsula. The largest of these, Nangnong (Lelang), in the northwest, will for the next 400 years remain a Chinese colonial bastion, and have manifold cultural and political effects on the native population. In the first century B.C., powerful Korean tribal clans begin to coalese in what will eventually become centralized states.
ca. 10th century B.C. The earlier comb-pattern wares are replaced by what is commonly termed "plain coarse pottery" (mumun), possibly as a result of the influence of new populations migrating to Korea from Manchuria and Siberia. This type of pottery typically has thicker walls and displays a wider variety of shapes, including jars with handles and bowls on high pedestals. The hardness of later mumun wares points to improvements in kiln technology.
ca. 10th century B.C. Metallurgy and bronze technology are introduced into the Korean peninsula, probably from the northern regions of the continental mainland. The dates of the beginning of bronze manufacture in Korea are uncertain, but by the seventh century B.C., a Bronze Age material culture, with influences from northeastern China as well as Siberia and Scythian bronze styles, flourishes on the peninsula. Korean bronzes contain a higher percentage of zinc than those of the neighboring bronze cultures. Bronze artifacts, found most frequently in burial sites, consist mainly of daggers, spearheads, small bells, and mirrors decorated with geometric patterns; excavations have also yielded bronze objects that perhaps served ritual functions.
ca. 900 B.C. Burial practices become more elaborate, a reflection of increasing social stratification. Dolmen tombs, formed of upright stones supporting a horizontal slab, are more numerous in Korea than in other parts of East Asia. Other new forms of burial are stone cists (underground burial chambers lined with stone) and earthenware jar coffins. The bronze objects, pottery, and jade ornaments recovered from dolmens and stone cists indicate that such tombs were reserved for the elite class.
ca. 6th century B.C. Burnished red wares, made of a fine iron-rich clay and characterized by a smooth, lustrous surface, appear during this period. The red color and sheen are produced by applying an iron-rich pigment such as ocher to the vessel and then burnishing the object before firing. While most of these wares are found in stone cist and dolmen tombs, recent excavations of residential sites reveal red burnished vessels in such forms as bowls and footed cups. Like the small globular jars uncovered from tombs, these are made of fine clay and have thin walls, and are probably intended primarily for ritual use. Burnished black wares in various shapes have also been found in tombs dating from the fourth to third century B.C., but in fewer numbers than the red wares.
ca. 5th century B.C. Eggplant-pattern jars, with rounded bodies and flared rims similar in shape to many red burnished wares, are decorated on their shoulders with the dark gray and brown elongated patterns that give this ware its name. This bold decoration, achieved by applying colored pigment on the clay body, represents a radical departure from the incised and applied-relief wares of the earlier Neolithic period. These types of wares are found only in Kyôngsang and Chôlla provinces, in the southern part of the peninsula.
4th century B.C. By this time, states with defined political structures have been established on the peninsula in the areas around the small walled-town states that were formed earlier with the advent of bronze implements. The most advanced of these states, Old Chosôn, is situated in the basins of the Liao and Taedong rivers, in the northwest.
ca. 300 B.C. Iron technology is introduced into Korea from China. Evidence suggests that iron is produced locally in the southern part of the peninsula by the second century B.C. According to Chinese accounts, iron from the Pyônhan region, in the lower Naktong River valley in the southeast, is valued throughout the peninsula and even attracts traders from Japan.
ca. 4th3rd century B.C. Examples of rock art generally believed to date to the late Bronze Age or early Iron Age have been discovered at sites in southeast Korea. The best known of these sites, at Pan'gudae, near Kyôngju in North Kyôngsang Province, portrays hunting and fishing scenes with drawings of human figures, animals such as deer, tiger, and boar, and whales and other marine life. Another site, at Ch'ônjôn-ri, features geometric patterns, including spirals, circles, and lozenges, along with deer, reindeer, and other animals. These petroglyphs, executed in pecking, engraving, and grinding techniques, have been interpreted as expressions of religious beliefs or practices such as sun worship.
ca. 194180 B.C. The state of Old Chosôn, which under pressure from the more powerful Chinese state of Yan enters a period of decline in the late fourth century B.C., falls to a new kingdom named Wiman Chosôn after its founder. Possessing superior military and economic strength, Wiman Chosôn proceeds to subjugate the neighboring states on the peninsula to the north, east, and south.
108 B.C. At the end of the second century B.C. the relatively passive transmission of Chinese culture to Korea by emulation and occasional immigration comes to an end. The powerful Chinese Han dynasty (206 B.C.220 A.D.), seeks to prevent the formation of alliances between its nomadic neighbors beyond the Great Wall and the people of southern Manchuria and northern Korea by armed conquest and colonization. In the wake of the initial military onslaught of 108 B.C. into Korea, Chinese authority extends down the peninsula as far as the Han River valley. Control of such an extensive area soon proves untenable, and a secure power base is established at the Lelang Commandery in northern Korea near modern P'yông'yang, which remains a Chinese colonial bastion for over 400 years.
1st century B.C. To the northeast of the Chinese commandery of Lelang, along the middle reaches of the Yalu River, lies the territory of the Koguryô, a warlike tribal people who pose a recurrent threat to Lelang. South of Lelang the peninsula is divided into three regions known collectively as the Samhan: Mahan, in the southwest, Pyônhan, in the south central area of the Naktong River basin, and Chinhan, in the southeast. These loose political confederations eventually evolve respectively into the Paekche Kingdom, the Kaya Federation, and the Silla Kingdom of the Three Kingdoms period.