During the Sui, Tang, and Song dynasties in China: 1) The Sui Dynasty reunified China in 589 and completed the Grand Canal connecting northern and southern China. 2) The Tang Dynasty expanded China's territory during its rule from 618 to 907. 3) The Song Dynasty faced threats from nomads in the north and saw a population doubling and agricultural and economic prosperity during its rule from 960 to 1279, including growth in cities, industry, and trade.