The Northern Song Dynasty (2.4.960-3.20.1127) is an era of Song Dynasty. It came to an end when its capital city, the city of KaiFeng, was conquered by enemies from the north. Later, the provisional capital of the Northern Song Dynasty was founded in Ying Tian Fu (present-day Nanjing of Jiangsu). Historically, the Song Dynasties include both the Northern and the Southern Song. It is named Northern to distinguish from the Southern, which resided mainly in Southern China. Emperor Taizu of Song elaborated a mutiny and usurped the throne of the Later Zhou (the last in a succession of five dynasties), which marked the beginning of the Dynasty. In 1127, its capital city Kaifeng fell into the hand of the state of Jin, during which time the emperor and his family all fell captivated. The Northern Song came to its end the next year. It was ruled by nine emperors, and lasted for 127 years.
The ruled area of the Northern Song extended to the southeastern coast. Its Northern Border with the Liao state was the Hai River, Ba Zhou city, Hebei province, and Yanmen Pass, Shanxi (Jin) province, an essential pass of the Great wall. Its reign reached northwest to the Hengshan Mountain in Shaanxi (Shan/Qin), the east of Gansu province, and the Huangshui River of Qinghai, all the way to the border with the state of Liao. In the west, it shared the boundary line of Min Mountains and Dadu River (Sichuan) with Tibet and Dali Kingdom. It was also adjacent with Vietnam across Guangxi province. Still, the Northern Song Dynasty has been the smallest in terms of land area among all the united empires that established on the vast Central Plains. As was recorded by Taiping Huanyu Ji, the population of the Northern Song Dynasty exploded from 32,500,000 in 980 to 100,001,200 in 1110.
Taizu, the first emperor of Song, Zhao Kuang Yin was a professional soldier. he was a Lifeguard in charge of the troops in front of the emperor's palace in the Later Zhou. Zhao had become an essential military figure during the reign of emperor Shizong owing to his outstanding military exploits. After Shizong died, the young Gongdi emperor ascended the throne. Zhao later seized power through Chenqiao Mutiny, and established the Song. He adopted an authoritarian centralized system to uproot the potential dictatorship and autocracy of senior officials, which had long been a threat ever since mid Tang Dynasty, and to solidify the authoritarian central government, a contributing factor to the stability and growth of the feudal social economy. On the other hand, the redundant bureaucracy and unnecessary official posts led to a terrible decline in efficiency and subsequently financial difficulties. In the field of military, The Northern Song expanded troops, weakened the military power of generals by separating the power to different persons, and shortened their service term at one official post so that they would not have the chance to accumulate that much power before it threatened the central. The constant change of the general, however, resulted in the decline of fighting capacity of the soldiers, and the Northern Song troops had suffered repeated defeats against minority groups like the Liao and Western Xia. The frontier defense thus became empty and feeble, which was detrimental to national security. Overall, the authoritarian centralized system had to some extents contributed to the unification and stability of the feudal state, preventing the local separatism and peasant revolts from happening, but it also foreshadowed the deepening impoverished and enfeebled from the mid Northern Song.