What might have been the purpose of the walls in Great Zimbabwe?

Some experts have tried to come up with a list of plausible uses of the various structures at Great Zimbabwe; The great Zimbabwe walls were called The Great Enclosure or Imbahuru and their purpose were; Defence- that is to withstand any attacks from the state’s enemies; They also served as the residence of the ruling family; They separated the ruling class from the commoners. The Great Enclosure was more luxurious than those in the valley where commoners lived.

there are hundreds of postives ways to unite a country with another country here are a   few

1 peace treaty's peace treatys

are basically a document signing a allliance with one country and another.

2 gift

what i mean by this is for example how the french gave the americans the statue of libery a gift of peace.