Excerpts from Books and Wikipedia
"Founded by Emperor Wen of Sui, the Sui dynasty capital was Chang'an (...) and later Luoyang (605–618). Emperors Wen and Yang undertook various centralized reforms . . . They also spread and encouraged Buddhism throughout the empire. By the middle of the dynasty, the newly unified empire entered a golden age of prosperity with vast agricultural surplus that supported rapid population growth. A lasting legacy of the Sui dynasty was the Grand Canal. With the eastern capital Luoyang at the center of the network, it linked the west-lying capital Chang'an to the economic and agricultural centers of the east towards Hangzhou, and to the northern border near modern Beijing. . . . After a series of costly and disastrous military campaigns against Goguryeo, one of the Three Kingdoms of Korea, ended in defeat by 614, the dynasty disintegrated under a series of popular revolts culminating in the assassination of Emperor Yang by his ministers in 618." [Wikipedia]