Prehistory, traditionally, has meant the era before written documents. For "western civilization," this period had ended about five thousand years ago. In the Americas, it ended with the arrival of the Europeans. For Asia, .... The term "prehistory" was widely used in this way (meaning the era before written documents) during the period that the discipline of history was professionalizing in order to distinguish the discipline from other para-historical disciplines such as archeology, anthropology, biology, and geology, that while historical in descriptive method, did not use written documents as their data source. In the past thirty or so years, historians have become more sophisticated in their methods and have developed interpretative frameworks and tools to allow them to begin to understand and integrate non-written data into the historical record. As a descriptive term, Prehistory is a complicated concept because it supposes a period of time (which by definition should have a history) before things started having a history. Additionally, "pre-history" supposes that there will be a time of "post-history" (which, again, contra-dictorially, would be a historical period of time without a history) and that we currently inhabit the "historical age"—problematical assumptions at the very least.