Why is the land of North Korea so vast?

From the 2nd century BC to AD, there were mainly Fuyu, Koguryo, Woju, Donglai and other tribal countries in the northern part of the Korean Peninsula. The Western Han Dynasty established four Han counties in this area, of which Fan Zhen and Lintun counties were quickly abolished, and Xuantu county was also transferred to Liaodong. At the same time, after the rise of the Yalu River basin, Koguryo began to gradually unify neighboring countries and annexed Lelang County. Please note that it is Koguryo, not Koryo. Goguryeo is different from Koryo. In 2007, China successfully applied for the World Heritage of Koguryo. )

In the southern part of the Korean Peninsula, Chen Guo developed into triple alliance composed of Mahan, Chen Han and Han Ji. In 18 BC, Baekje was established in Mahan and gradually replaced Mahan. Six departments of Chen and Han developed into Silla.

In the 4th century A.D., the Korean Peninsula formed the "Three Kingdoms Period of Korea" in which Koguryo, Silla and Baekje stood together.

Koguryo was the overlord of the peninsula in this period. During the reign of King Tai Hao and King Changshou in the 5th century A.D., Koguryo entered its heyday, and in the following 1 century, it still maintained a strong strength on the Korean Peninsula, controlling most of the Korean Peninsula and Liaodong Peninsula in the northeast of China. Since then, during the Sui and Tang Dynasties in China, Goguryeo has been at war with China and began to fall. In 668, it was destroyed by the joint forces of the Tang Dynasty and Silla. According to the inscription in Koguryo's "The Monument to the King of Shantai", King Koguryo forced Baekje and Silla to submit to Koguryo and repelled the Japanese invasion of Silla.

Baekje was founded by two sons of Koguryo founder Zhu Meng in today's Seoul. Baekje annexed Mahan tribe, which reached its peak in the 4th century and ruled most of the western part of the Korean peninsula. After being attacked by Goguryeo's expansion, the capital was forced to move to Jinxiong (now Duke of Zhou) and then to Si Tong (now Fuyu County).

In the first 57 years, Silla unified the southeast of the Korean peninsula, annexed the Chen and Han tribes and established a country. Before the middle of the 6th century, Silla annexed Garda. In 668, after Silla conquered Baekje with the help of the Tang Dynasty, Koguryo was destroyed and most parts of the Korean Peninsula were unified.

Silla's territory arrived in the Yellow Sea after it was seized from Baekje and occupied by Koguryo. Silla began to form an alliance with the Tang Dynasty against Baekje and Koguryo. In 660 AD, the Tang Dynasty combined Silla to destroy Baekje, attacked Koguryo the following year, and stationed around Pyongyang for a long time. In 668, he sent troops again and finally conquered Pyongyang in September of that year. General Xue established Anton in Koguryo and Baekje. Since then, the Koguryo regime has withdrawn from the historical stage.

After the war between Silla and the Tang Dynasty in 670-676, Silla occupied Baekje's hometown and a small part of the original Koguryo territory, unified the area south of the Datong River on the Korean Peninsula, made Gyeongju its capital, and ruled by imitating the state system of the Tang Dynasty. (Please note that it is "a small part of the original Koguryo territory")