Democracy was developed in which ancient civilization

Democracy is thought to have developed first in ancient Greece.

There are some attempts to identify some versions of democracy before this, but Greece is still the one place that is most accepted  by the scholars.

especially Athens in 6th century BCE is thought to be the place where democracy was first developed and flourished - but there were also some other, smaller city-states in Greece with democratic rule.

The answer is an appellate court.