A general term that can be used with both positive and negative connotations for any scholarly practice dedicated to revising an established position. In Marxism, revisionism is used in a pejorative sense to describe any deviation from the central tenets of Marx's thought (e.g. his theory that the transition to socialism will require a revolution). It is also used by communist leaders as a general term of political abuse in arguments between communist countries (e.g. Mao accused Khrushchev of being a revisionist for his de-Stalinization policies, while Albanian General Secretary Enver Hoxha accused the Maoists of being revisionists for normalizing relations with the US). In history, revisionism is generally reserved for those historians who seek to deny that major historical events such as genocides actually took place. The so-called Holocaust-deniers are one example, but there are many others. On a positive note, however, historians who seek to overturn the bias and exceptionalism of certain national histories are also known as revisionists, but they plainly serve an important purpose. In former colonial countries like the Americas and Australia, revisionist historians have played an crucial role in challenging popular misconceptions about indigenous peoples.