South Korea, officially the Republic of Korea

Three Kingdoms of Korea 
During 
the Proto–Three 
Kingdoms 
period, 
the 
states 
of Buyeo, Okjeo, Dongye, 
and Samhan occupied the whole Korean peninsula and southern Manchuria. From them, 
the Three Kingdoms of Korea emerged: Goguryeo, Baekje, and Silla. 
Goguryeo, the largest and most powerful among them, was a highly militaristic state
. 
and 
competed with various Chinese dynasties during its 700 years of history. Goguryeo experienced 
a golden age under Gwanggaeto the Great and his son Jangsu, who both subdued Baekje and 
Silla during their times, achieving a brief unification of the Three Kingdoms and becoming the 
most dominant power on the Korean Peninsula. In addition to contesting for control of the 
Korean Peninsula, Goguryeo had many military conflicts with various Chinese dynasties, most 
notably the Goguryeo–Sui War in which Goguryeo defeated a huge force said to number over a 
million men.
Baekje was a maritime power, which motivates some
[
to call it the "Phoenicia of East Asia".Its 
maritime ability was instrumental in the dissemination of Buddhism throughout East Asia and 
spreading continental culture to Japan. Baekje was once a great military power on the Korean 
Peninsula, especially during the time of Geunchogo, but was critically defeated by Gwanggaeto 
the Great and declined. Silla was the smallest and weakest of the three but used opportunistic 
pacts and alliances with the more powerful Korean kingdoms, and eventually Tang China, to its 
advantage.
The unification of the Three Kingdoms by Silla in 676 led to the Northern and Southern States 
period, in which Balhae controlled the northern parts of Goguryeo, and much of the Korean 
Peninsula was controlled by Later Silla. Relatinships between Korea and China remained 
relatively peaceful during this time. Balhae was founded by a Goguryeo general and formed as a 
successor state to Goguryeo. During its height, Balhae controlled most of Manchuria and parts of 
the Russian Far East and was called the "Prosperous Country in the East". 
Later Silla was a wealthy country, and its metropolitan capital of Gyeongju was the fourth 
largest city in the world. It experienced a golden age of art and culture, exemplified 

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by Hwangnyongsa, Seokguram, and the Emille Bell. It also carried on the maritime prowess of 
Baekje, and during the 8th and 9th centuries dominated the seas of East Asia and the trade 
between China, Korea and Japan, most notably during the time of Jang Bogo. In addition, Silla 
people made overseas communities in China on the Shandong Peninsula and the mouth of 
the Yangtze River. However, Later Silla weakened under internal strife and the revival 
of Baekje and Goguryeo, which led to the Later Three Kingdoms period in the late 9th century. 
Buddhism flourished during this time, and many Korean Buddhists gained great fame among 
Chinese Buddhists
[65]
 and contributed to Chinese Buddhism. Examples of significant Korean 
Buddhists from this period include Woncheuk, Wonhyo, Uisang, Musang, and Kim Gyo-gak. 
Kim was a Silla prince whose influence made Mount Jiuhua one of the Four Sacred 
Mountains of Chinese Buddhism.