Why were tang and song cities considered cultural centers of an international age

The period of the Tang Dynasty in China was remembered due to the great amount of progress in Chinese society. Cultural manifestations were numerous in publishings in literature and art. Its major cities were Chang'an, Luoyang, and Guangzhou. Chang'an was the dynasty's capital. It is believed that the Japanese city of Kyoto used it as a reference for its urban development.

Under the Song Dynasty, the Chinese invented gunpowder. There were also technological developments in the military. Main cities of the dynasty include the capital city of Bianjing. This city saw the introduction of the world's first form of paper money.

they both built pyramids.

the answer i chose to believe is 'harmony'