This map, revised in 2011, shows the indigenous language regions of Alaska. Related languages of neighboring Canada and Russia are also show. The language boundaries represent tradtional territories at approximately 1900, though some shifts in language boundaries have occurred since that time. Boundaries are defined based on the similarity of sound systems and the ability of speakers from different regions to understand each other. Although based largely, including language definitions, boundaries and insets, on Michael Krauss's 1974 and 1982 Native Peoples and Languages of Alaska map this map differs in several ways. This map does not indicate indigenous populations or speaker numbers; language status in each village or size of village; and dialect boundaries. Finally, several languages have been revised to reflect current usage.