The earliest foundation of Beijing was Youzhou City in the Tang Dynasty. in the following thousand years, Beijing had four large-scale development, or expansion, or new construction, namely, the capital of the Yuan Dynasty and the capital of the Yuan Dynasty. the inner city built in the early Ming Dynasty and the outer city built after the middle of the Ming Dynasty, the convex wall of Beijing was completed in this way. The Qing Dynasty inherited Beijing of the Ming Dynasty, leaving the overall layout system unchanged until modern times.
Beijing expanded its outer city in the early Ming Dynasty can be seen to be correct.