The Mongolian gull was formally described in 1925 by the Russian ornithologist Petr Sushkin based on specimens collected near the Üüreg Lake in northwest Mongolia.

He considered it to be a subspecies of the then broad view of the herring gull and coined the trinomial name Larus argentatus mongolicus.

There is some variation within the species, with darker grey towards the west of the range in NW Mongolia, and paler in birds from Lake Baikal; these last can be almost as pale as European herring gull of the subspecies L. a.

[2] In winter it migrates southeast to the coasts of Japan, the Korean Peninsula, eastern and southern China, Taiwan, and northern Vietnam.

[1][2] Reports from the Indian Ocean are considered unlikely, with sightings claimed from India, Pakistan and the Persian Gulf being unreliable; there are no ringing recoveries from that region, only from the Pacific coasts of Asia.