"D. d. cashmiriensis" has brighter blue upperparts and a whiter rump than the slightly larger nominate race. The third, smallest, race is "D. d. nigrimentalis". All three subspecies can be distinguished from the similar Nepal house martin by the latter species' black chin, black undertail coverts and much squarer tail. The Asian house martin is more similar to the common house martin, but is darker underneath and has a less deeply forked tail. Confusion is most likely between adult male Asian house martins, which have paler underparts, and the eastern race of common house martin, "D. urbicum lagopodum" which has a less forked tail than the western subspecies, although it still shows a more pronounced fork than Asian.