Spread zone

A spread zone is an area whose geographical characteristics are conducive to the spread of language families across a large area, resulting in consecutive language replacement and low linguistic diversity (as opposed to a residual zone). An example of a spread zone is northern Eurasia, where large areas (the Eurasian Steppe in particular) are covered by relatively few language families, most of which are possibly related to each other in a single superfamily (see Mitian).