A current model of rain forest population diversification in Sundaland specifies east-west vicariance into refugia during the early Pleistocene. In some taxa, this division was followed by dispersal and secondary contact on Borneo in the late Pleistocene. To investigate genetic, morphological, spatial, and temporal characteristics of the model, we compared genomic population and plumage variation among four bird species with known east-west mtDNA and plumage division.