Different parts of the world practise archaeology in different ways. The way in which the profession of archaeology is structured can be different, and also the methods used and the focus of research. On the other hand, the boundaries and existence of many modern countries go back only to the nineteenth or twentieth centuries. The heritage of the past may be claimed by them as part of their identities, but can also be seen as a common human heritage, existing from a time before modern nations existed. Archaeology is international in scope and increasingly international in practice.