By the end of the Southern and Northern Dynasties, China had been divided for 270 years. People looked forward to a unified country but no emperor in the Northern Zhou or the Southern Chen was able to accomplish this. It was not until Yang Jian got the throne and founded the Sui Dynasty.
Yang Jian, from an aristocrat family in the Northern Zhou of Northern Dynasty, was Emperor Xuan's Chancellor of Military Affairs. In 580, when the eight years old Prince ascended the throne, Yang jian was made Prime Minister and took charge of both military and administrative affairs. After his suppression of the separatist forces in Henan, Hubei and Sichuan, In 581, he forced Emperor Jing to give up the kingship to him and proclaimed himself emperor and named his empire the Sui. As Emperor Wen of the Sui, he immediately carried out his military plans for unification. He first made peace with the Western Turks and resettled the Eastern Turks, hence trouble free at the north of China. Then he attacked the Chen in the south by appointing Yang Guang as marshal. Yang Guang collected his forces in Anhui to make preparations for crossing the Yangtze River. In 589, Sui forces advanced crossing the Yangtze River from Caishi and Guangling respectively; then they quickly attacked and captured Jiankang where the capital of Chen. The Chen forces collapsed and its emperor surrendered. All forces in the south successively pledged allegiance to the Sui. It took Emperor Wen less than four months to unify the north and the south. He reunified the whole of China, bringing about the second major nationwide unification in Chinese history.
Political System and Economy of the Sui Dynasty
Emperor Wen undertook a series of measures to develop the economy, recover production and consolidate the unification. He resumed the system of Han-Wei Dynasties and established an administrative system centering on three ministries and six departments. Among the three ministries, the Secretariat was in charge of decision-making, the Grand council examined and approved the decrees and the Chancery was responsible for the administration of daily affairs. Under the Chancery, six departments were set up, including ministry of Official Personal Affairs, Ministry of Rites, Department of War, Board of Revenue and Population, Ministry of Punishments and Ministry of Engineering, These six departments took charge of different affairs respectively. Local administrative divisions were also changed - from the three-level system (prefectures, sub-prefectures, and counties) to a two-level system (prefectures and counties). Emperor Wen abolished the system of nine ranks with wealthy families holding power and set up institutions of learning in prefectures and counties and selected officials through examinations. The imperial examination system was improved. He also reformed the military enlistment system. The domicile of soldiers was included in the prefectures and counties together with that of the people so that the source of soldiers was broadened and the cost of maintaining an army was saved. He issued new orders to implement the land equalization system and to mint the five-zhu coins, and standardized weights and measures. Taxes were reduced, domiciliary register was cleared up. He entrusted able man with important positions to develop agriculture and to construct water conservancy as well as irrigation systems, which helped reviving handicraft industry and commerce. The completion of the Guangtong Channel made it more convenient for water transport. During the Renshou years, the number of families in the country reached from around five million to seven million, the granaries were full and the society was peaceful and prosperous.
In the 20th year of Kaihuang (600), Emperor Wen deposed Heir-Prince Yang Yong and conferred that title upon his second son Yang Guang. In the 4th year of Renshou (604), Emperor Wen died unexpectedly and Yang Guang became Emperor Yang. He started to build the eastern capital Luoyang and dig the Great Canal from Zhuijun (now Beijing) to Yuhang (now Hangzhou). It's about 2000 meters. Luoyang became a political, military and center of transportation and the construction of the Great Canal strengthened the economic relationship between the northern and southern China. He conscripted large numbers of laborers to work on the Great Wall. He sent massive force to attack Korea three times. He traveled about the country and made three inspection tours to Jiangdu. All these made the people extremely miserable and exhausted the state. In the countryside, many people escaped from military service and forced labor. Refugees were found everywhere. In 611, a peasant uprising led by Wang Bo broke out in Shandong, which was followed by many others all over the country. Yang Xuangan, an aristocrat, also rose in revolt, which was a sign of split within the ruling class. During the battle with the Sui army, the rebellious peasants gradually fell into three main forces - the Wagang Army in the central led by Li Mi, the Xia Army in the north led by Dou Jiande and the Wu Army in the south led by Du Fuwei. In 617, the Wagang Army attacked the Eastern Capital. At that time, Emperor Yang was journeying south to Jiangdu, with Tong the Prince of Yue who was defending the Eastern Capital. Li Yuan of Taiyuan, Shanxi, took the opportunity to lead an army into Chang'an and installed You the Prince of Dai as emperor while making himself Prime Minister. In 618, Yuwen Huaji in Jiangdu staged a mutiny and hanged Emperor Yang. Li Yuan immediately proclaimed himself emperor in Chang'an (now Xian) and established the Tang Dynasty after he heard the news. Almost immediately, the powerful lords rose one after another. In the next few years, the Tang army wiped out the peasant as well as local separatist forces. The whole country was once again unified.
Science and Culture of the Sui Dynasty
From the reign of Emperor Wen to the early years of Emperor Yang, the social economy underwent rapid recovery and development. Science and cultural achievements were also outstanding. Craftsman Li Chun built the world-famous stone arch bridge Zhaozhou Bridge, more than 1,200 years earlier than any similar bridge built by the Europeans. Master Technologist Yuwen Kai led the construction of the Daxing City, laying foundation for the building of the Tang’s Chang’an City, Signigicant progress was also made in medicine. Many achievements were also attained in culture, particularly in the study of Confucianism and of Buddhism. Sino-foreign cultural communications also developed fast. Messengers from East-Asian countries like Xinluo, Baiji and Japan made frequent visits to China. A number of Japanese monks and students came to study. Emperor Yang sent Fei Ju to the west to invite merchants from different places to visit and trade in China. Emissaries were also sent to countries like Zhenla and Chitu in Southeast Asia. China's status and influence in the Asian area improved a lot during the Sui Dynasty