It is morally correct, and reflects basic property laws, that stolen or looted property should be returned to its rightful owner. Cultural objects belong together with the cultures that created them; these objects are a crucial part of contemporary cultural and political identity.
Why should cultural artifacts be returned?
They have a unique connection with the place where they were produced and are an essential part of the cultural history of that area. That link should be honoured by returning the artefacts to the place where they were originally made and used.