this time were weapons such as swords, daggers, and spearheads. Also, ritual items such as mirrors, bells, and rattles were made. These items were buried in dolmens with the cultural elite. Additionally, iron-rich red pots began to be created around circa 6th century. Comma-shaped beads, usually made from nephrite, known as kokkok have also been found in dolmen burials. Kokkok may be carved to imitate bear claws. Another Siberian influence can be seen in rock drawings of animals that display a "life line" in the X-ray style of Siberian art. Iron Age The Korean Iron Age began around the 5th to 4th century BC with the arrival of the Chinese iron culture; it most likely began through the contacts with the North-East Chinese state of Yan and was later developed through the Chinese Lelang Commandery. Koreans have always tried to import Chinese technology and reshaped it in their own in order to make it uniquely Korean and in order to develop new technology. The introduction of Chinese iron culture contributed to the rapid development of ancient Korea. The Koreans then localized the Chinese iron culture into a new form of Korean iron casting technology. By 300 BC, iron was widely used in Korea; however, the Iron culture of Korea continued to be deeply influenced by China which is attested by numerous archeological artifacts. Korean pottery advanced with the introduction of the potters wheel and climbing kiln firing. Three Kingdoms This period began circa 57 BC to 668 AD. Three Korean kingdoms, Goguryeo, Baekje, and Silla vied for control over the peninsula. Goguryeo Buddhist missionaries introduced Buddhism to Goguryeo in 372 CE, which then covered the central and southern parts of Manchuria and the northern half of modern-day Korea. As Buddhism infiltrated the culture, Goguryeo kings began commissioning art and architecture dedicated to Buddha. A notable aspect of Goguryeo art are tomb murals that vividly depict everyday aspects of life in the Korean ancient kingdom as well as its culture. UNESCO designated the Complex of Koguryo Tombs as a World Heritage Site. Goguryeo painting also inspired the creation of similar works in other parts of East Asia, like Japan. This can be seen in the wall murals of Horyu-ji which show its Goguryeo influence. Mural painting also spread to the other two kingdoms. These murals reveal valuable clues about the Goguryeo kingdom including the importance of Buddhism, its architecture, and the