Looking back at the heyday of Kaiyuan, there are still thousands of families in the small town. What does Kaiyuan mean?

This is a poem by Du Fu. The original poem is:

1: Looking back at the heyday of Kaiyuan, there were thousands of families in Xiaoyi. Rice fertilizer, millet white,

Public and private granaries are abundant. There are no wolves and tigers on the road in Kyushu, which is a good day to travel.

Wan Qi, Lu Mao, driver class, male plow female mulberry. The sage in the palace played the cloud gate,

All the friends in the world are stuck. There has been no catastrophe for more than 100 years, and Uncle Sun has learned Xiao He's law.

Do you smell a piece of silk worth 10 thousand yuan? Today, a field is bleeding. Luoyang Palace was burnt down,

The ancestral hall has newly demolished the fox and rabbit points. I can't bear to ask my age, but I'm afraid I'll leave at the beginning.

My junior minister, Lu Chong, was powerless, and the imperial court remembered his official title. Zhou Xuan looked up at my emperor:

Sprinkle blood, Jianghan is exhausted.

2. What do you mean by that word?

It refers to the golden age of Kaiyuan, that is, when Emperor Taizong was in power. Kaiyuan is the title of Emperor Taizong!

Please refer to!