What does it mean that Beijing started as Peiping and Nanjing left as Jinling?

Yin Lichuan, a freelance writer, was the first person to write similar sentences. As the blog says, when it snows, Beijing becomes Beiping. That year, the snow in Beijing was very thick and looked flat, and all the smells were covered up, which made people feel that they were in a foreign land and had a lot of thoughts! So there is that sentence in the blog. After the snow, the customs of Qinhuai River are as good as those of Beiping, so it is not difficult to understand what it means for Nanjing to become Jinling.

Title: At first Beijing was Beiping, and Nanjing became Jinling as soon as it left. The author should have some feelings similar to Yin Lichuan's, and combine what he has seen and heard to form a * * * song before writing. What kind of mood is specific, you need to know the author's situation at that time to understand it in detail, which is beyond the understanding of ordinary people.