The Buddhas of Bamiyan are the extreme case, where the local rulers destroyed cultural heritage. There are also some items that can not reasonably been repatriated. But there are hundereds of items from Greece, Turkey, Egypt or reltively stable former colonies in museums in Western Europe. And then even famous institutions like the British museum manage to loose precious items.
The Buddhas of Bamiyan are the extreme case, where the local rulers destroyed cultural heritage. There are also some items that can not reasonably been repatriated. But there are hundereds of items from Greece, Turkey, Egypt or reltively stable former colonies in museums in Western Europe. And then even famous institutions like the British museum manage to loose precious items.