China was reunified in A.D. 589 by the short-livedSui dynasty (A.D. 581-617), which has often been compared to the earlierQin dynasty in tenure and the ruthlessness of its accomplishments. TheSui dynasty's early demise was attributed to the government's tyrannicaldemands on the people, who bore the crushing burden of taxes and compulsorylabor. These resources were overstrained in the completion of the GrandCanal --a monumental engineering feat--and in the undertaking of otherconstruction projects, including the reconstruction of the Great Wall.Weakened by costly and disastrous military campaigns against Korea in theearly seventh century, the dynasty disintegrated through a combinationof popular revolts, disloyalty, and assassination.
Sui Dynasty rulers were partly Normads, aswas Tang Dynasty. Despite the fact that the royal houses of Sui and succeedingTang were not entirely Han Chinese, both of these dynasties are consideredto be Chinese, as opposed to the Mongols and Manchus later on.
Picture of Greant Canal.. the only thing thatis uniquely Sui is the construction of Grand Canal, connecting Yellow andYangtze two major eastward waterways by starting from Beijing all the waydown to Hangzhou (link here), thus make nation wide commerce possible forthe next prosperious Tang