establish, one of nine empire divisions
兗 centers on the idea of establishing or founding something, and it also names one of the nine traditional divisions of the Chinese empire. The two meanings are linked by the sense of a defined, established territory.
The exact historical development of 兗 is uncertain. It appears to combine 亠 (a lid or top) with 兌, which may have contributed sound or meaning, but the original construction is not clearly established.
The top 亠 looks like a roof or cover, and the bottom 兌 suggests a defined area with 口 (mouth/opening) and 儿 (legs). Imagine establishing a settlement by putting a roof over a designated territory.
For エン, picture the established territory as an 'en'closure: en -> エン, and the roof 亠 covers the defined area.