Kaiyuan (713 - 741) was the earliest reign title of Li Longji, Emperor Xuanzong (712 - 756). Through over 100 years of develoment from the beginning of Zhengguan reign of Taizong to the end of Kaiyuan reign, Tang Dynasty became unprecedentedly prosperous. So this period was referred to as the "Prosperous Kaiyuan Period".

Emeror Xuanzong was the gradson of Wu Zetian, but he modeled his rule on that of Emperor Taizong. He made use of capable people, listened to his ministers advice and devoted himself to state affairs. He demonstrated his capablity with prompt measures one year by combating a plague of locusts in northern China, and saved people from starvation.

The renowned poet Du Fu described the prosperity of that time in his poem Remenbering the Past:

"Remenber the good old Kaiyuan days
When even a small county had ten thousand households
The rice shone and the corn was white
And granaries of state and people burst with grain alike."

During the Kaiyuan Period, the society was stable and peaceful, and commerce and transportation were highly developed. Yangzhou, located where the Grand Canal meets the Yangtze River, was a bustling city where merchants from all over China and abroad converged. Chang'an, the capital of Tang Dynasty, was then one of the world's great metropolises. Envoys, merchants, scholars and artisans of many countries flocked to Chang'an to trade, and to study the advanced culture and technology of Tang Dynasty.