Greylag goose the western greylag goose, breeds in Iceland and north and central Europe; "A. a. rubrirostris", the eastern greylag goose, breeds in Romania, Turkey and Russia eastwards to northeastern China. The two subspecies intergrade where their ranges meet. The greylag goose sometimes hybridises with other species of goose including the barnacle goose ("Branta leucopsis") and the Canada goose ("Branta canadensis"), and occasionally with the mute swan ("Cygnus olor"). The greylag goose was one of the first animals to be domesticated; this happened at least 3000 years ago in Ancient Egypt, the domestic breed being known as "A. a. domesticus". As the
Branta correctly assigned – meaning that the genus "Anser" was once much more widespread than today and that it coexisted with "Branta" in freshwater habitat which it today does only most rarely – is not clear. Especially in the case of "B. dickeyi" and "B. howardae", doubts have been expressed about its correct generic assignment. The former ""Branta" minuscula" is now placed with the prehistoric American shelducks, "Anabernicula". On the other hand, a goose fossil from the Early-Middle Pleistocene of El Salvador is highly similar to "Anser" and given its age and biogeography it is likely to belong to that genus