What is the next sentence of "the desert is lonely and straight"? Which poem is it from?

The next sentence in "Lonely Smoke in the Desert" is that the long river sets the yen.

This poem comes from Wang Wei's "To the Fortress", the original text:

Riding a bike to visit the border and passing through Juyan County.

Levy Peng, return the geese to Wu.

The vast desert is lonely, and the Yellow River sets the yen.

When I arrived at the small pass, I met a spy waiting for the knight and told me that Dou Hu was in Yan.

1. The poem describes the flatness and vastness of deserts and long rivers, thus depicting a magnificent natural landscape outside the Great Wall. The magic of its seiko lies in the high artistic generalization of the space in the vast area beyond the Great Wall: the words "desert" and "long river" are vigorous and vigorous, which are a lot of smears, summarizing these two natural images so truly, naturally, accurately and vividly; And succinctly and skillfully make them complement each other and complement each other. It is because of the "desert" that the "river" is long; It is precisely because of the length of the river that the desert is great. The words "big" and "long" are extraordinary in the ordinary, like hit the floor with iron pillars. 2. This poem vividly depicts the magnificent scenery beyond the Great Wall with only the word 10, which Wang Guowei, a master of Chinese studies, called "the wonders of the ages".