Excerpt from Dunhuang Recommendation

When establishing and keeping up to date, on the basis of national inventories of protected cultural property, a list of important cultural property whose export would constitute an impoverishment of the national cultural heritage, states should consider the specific characteristics of archaeological objects.

Because such objects are usually never recorded and, once removed, it is extremely hard to identify them and prove that they have been unlawfully excavated. States may include them in the national inventories by using a categorization system classified by region and epoch or any other suitable archeological reference, if necessary, with a descriptive explanation;

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