Since the 20th century, the study of prehistory is considered essential to avoid history's implicit exclusion of certain civilizations, such as those of Sub-Saharan Africa and pre-Columbian America.
自從二十世紀起，研究者開始重視史前的研究，以免歷史研究隱性的排除一些特定的文明，例如撒哈拉以南非洲及前哥倫布時期的美洲。