The word "Cheng" is relatively stable in Oracle bone inscriptions and Li Wenzhong in the early Jin Dynasty.
"Cheng" is a word pronounced from E to D. Component "E" is not common in Chinese characters, although the word itself is a common word in ancient times. Because people don't often participate in the word formation of Chinese characters, when writing the word "E" or even the word "E" itself, people consciously or unconsciously draw it closer to another word "Ge" with similar glyph, common and strong word formation ability. Besides, "E" is based on "Ge", and the blade is replaced by an axe.
The following figure shows an example of cursive script.