Bai Lao refers to shrike, also known as anchovy or thrush. This poem is about swallows and birds flying in the sky, flying west and flying east.

This sentence comes from a poem by Cen Can, a poet in the Tang Dynasty, "Send the king to be a shogunate in Huaixi".

Sending the King to the West Shogunate is one of the works of the Tang Dynasty poets. ? The author cén shēn (about 7 15-770), whose ancestral home is Nanyang (now Xinye, Henan), is a famous frontier poet in Tang Dynasty. His poems are full of romantic features, and he is especially good at seven-character quatrains.