How did writing help unite China?

Qin unified the writing system throughput its empire, so that people speaking different dialects of Chinese (there are many, and not understandable to someone else speaking another dialect) can still communicate by reading and writing; that is, the literary class is united by the bond of a common script.

Explanation:

:-)

the language dates from the contacts of arabian traders with the inhabitants of the east coast of africa over many centuries. under arab influence, swahili originated as a lingua franca used by several closely related bantu-speaking tribal groups.