Some of Gu Yun's letters to Chang Geng were pure private letters, some were advising Yan Wang about business. Chang Geng was very experienced. He knew whether it was public or private when he touched the envelope with his hand before opening. Gu Yun's business letter was usually a thin piece of paper, with only a few words. He was a little disappointed when he received the letter from the Black Eagle messenger, because it was very thin to the touch, perhaps there would be no private words.

Chang Geng ordered the Black Eagle: "Perhaps Marshal Gu's side is still unaware. I'm leaving for the capital today. I've finished handing over the duties in Jiangbei. Please let him know after you return."

Then he opened the letter in front of the crowd.

There was really only one piece of paper inside, and a hand was drawn on it. Gu Yun wrote a line: "Take one palm and send it to Jiangbei, to measure the width of the other's waist for me."

Everyone in confusion looked at Yan Wang, not knowing what he was reading that took so long. Then, his face reddened.

https://www.northwestflower.net/sha-po-lang/book-3/chapter-15-conclusion/15-ii

In the ninth year of Long An, Jia Lai Ying Huo died. The Crown Prince succeeded the throne and officially announced their surrender on behalf of the Eighteen Tribes. The new Wolf King relinquished his royal title, knelt on his knees and kowtowed to the Emperor's decree. All Eighteen Tribes with small populations and sparse land were incorporated into the northernmost province of Shuobei of Great Liang. All the surrendered nobles were controlled by the governor of Shuobei.

At this time, the Eighteen Tribes no longer paid tribute to the imperial court and were integrated into the general tax revenue. The vast Ziliujin fields would be mined and transported by the special institution established by the imperial court.

The whole country of Great Liang celebrated.

Shen Yi stayed for the time being to hand over the duties, while Gu Yun had to return to the capital for his report. Cao Niangzi joined him. Chen Qing Xu had just made a copy of the complete secret art of the goddess, but she still had not digested it yet, so she also bid farewell to return to the Chen family.

Before leaving, Gu Yun called her to one side. At first, he wanted to ask if there was a certain possibility that there would be an antidote. Later, he thought it was an unnecessary question. Chen Qing Xu, a responsible person, would never confirm it beforehand. At most, she would say ‘I will try my best’. In this way, there was nothing else to say. In the end, he thanked Chen Qing Xu very solemnly and added: "Everything depends on Miss Chen."