Caomumin (螬牧民) are one of the officially-recognized constituent ethnic groups of the Earth Kingdom. They are nomadic (over very long ranges) and their origin is uncertain, but generally thought to be on the Southern Continent. Their legends claim that they were the indigenous inhabitants of the land where Omashu now stands, but these events are in such remote antiquity that archaeology has yet to find any evidence of this.
The Caomumin are named for their most distinctive practice, that of using the Giant Rhinoceros Beetle as a pack animal for overland trade and migration. Their movements are linked to the various biological needs of the beetles, which are unusually desert-adapted but vulnerable to cold temperatures. They lay eggs in the desert, with their huge larvae eating roots and plants. The larvae have an exceedingly slow basal rate of metabolism and take about fifty to seventy years to go from an egg to the imago, with about three years spend as a pupa. The larvae can grow faster in a richer environment, but are very vulnerable to pathogens that flourish outside arid environments, so the Caomumin usually bury their beetles' eggs in the Hanwang and Siwang deserts or in the desert environs of Great Omashu.
Since the exile of the Nara Clan of Yonggan to the Hanwang desert, it has become less suitable for Beetle-raising; the Nara introduced the dwarf badgermole to the region and this animal is an enthusiastic predator of both the larval form of the beetle and even the adult form, though the latter is generally less of a problem since above-ground confrontations can often be prevented by the keepers of the animals.
The Giant Rhinoceros Beetle is venerated by the Caomumin and killing it is forbidden. They do eat other animals, however, including insects, and use the cast-off parts of the Beetle and larvae, fashioning chitin plates into useful articles. Adult men wear distinctive helmets styled after a beetle, which leads to the exonym "beetle headed merchants." Their legends claim the helmets were devised by a culture hero in imitation of the appearance of the "sour beetle," and protected the wearers from predation by giant gilicorns. They practice their own variety of animist shamanism, under syncretic influence from Central Earth Kingdom folk religion.
Overland trade is the main industry of the Caomumin; they compete with the Ganjinese in the North and West and dominate desert trade, as their pack animals fare better than ostrich horses in the desert.