In linguistics, a linkage is a group of undoubtedly related languages for which no proto-language can be reconstructed. Malcolm Ross, who coined the term, defined it as “a group of communalects which have arisen by dialect differentiation” (Ross 1988, p. 8).
Common to linkages are defining features absent from its geographic extremes. A linkage may result when the members of a dialect chain diverge while sharing subsequent innovations.
An example of a linkage is the one formed the Central Malayo-Polynesian languages of the Banda Sea (a sea in the South Moluccas in Indonesia).[1] The Central–Eastern Malayo-Polynesian languages are commonly divided into two branches, Central MP and Eastern MP, each having certain defining features that unify them and distinguish them from the other. However, while proto-Eastern and proto-Central–Eastern MP languages can be reconstructed (the sibling and parent of Central MP, respectively), a proto-Central MP language reconstruction does not seem feasible. It may be that the branches of Central MP are each as old as Eastern MP, but that they went on to exchange features that are now considered to define them as a family. In Eastern MP, common features can be assumed to have been present in the ancestral language, but this is not the case for Central MP.