By 15,000 BBY, the inhabitants had evolved to the point when they could be considered a separate species from their Duros ancestors. The genetic differences from the Duros that the Neimoidians developed were attributed the features of the planet, including its heavier gravity, dimmer sun, humidity, and perpetual fog and mist.
A settlement on Neimoidia.
Neimoidia was ruled by a Trade Monarch, reflecting the Neimoidian's obsession with trade, commerce, and money. That was also present in the Neimoidian Inner Circle, the government/legislature of the planet. The Neimoidians established purse worlds on nearby Cato Neimoidia, Deko Neimoidia, and Koru Neimoidia. Neimoidia was populated by the less capable and aggressive members of the species, all others moving off-world as soon as possible. Many low-level worker drones were kept malnourished so as to never reach full mental maturity. Combined with the planet's natural unpleasantness, it was usual for Neimoidians to choose not to return home unless absolutely necessary.
By 4,800 BBY, the Neimoidians locked up the distribution rights of newly-discovered ryll spice from Ryloth. Their irresponsible distribution of this drug led to the Gank Massacres, including the extinction of the Porporites.
The Neimoidians helped found the Trade Federation in 350 BBY as a cartel of merchants and businessmen, although their defense force may have been some centuries older.
During the Clone Wars, the Republic retook Neimoidia and its purse worlds from the Separatists in 19 BBY. During the battle, Neimoidia was ravaged, and the destruction of many Neimoidian grub-hatcheries would affect the Neimoidian species.
Later, Viceroy Gunray and Settlement OfficerRune Haako were killed on Mustafar by Darth Vader. With the rise of the New Order, the Trade Federation was disbanded after Acting Viceroy Sentepeth Findos signed a treaty on Neimoidia, and Neimoidians began to adopt the culture of the baseline Duros to disassociate themselves with the Trade Federation's shameful legacy. Afterward, Neimoidians rarely traveled, unless shifty dealings were afoot.
In 6 ABY, Neimoidia was quarantined due to viruses. This was not the first time such a precaution had been taken; numerous diseases and viruses originated on the planet, with the Neimoidians propagating them throughout the galaxy. The Intestinal Revenge of Bars Barka, which led to severe weight loss among Ubese colonists, as well as Great Pandemic of Deersheba, both called Neimoidia home. According to a joke made by Ebenn Q3 Baobab, onetime doctor for a Neimoidian fleet, "the principal export of the Neimoidian home planet is Brainworm Rot Type C".
Neimoidia was known for its manax tree orchards and fungus farms, tended by harvester beetles. Such orchards and farms, as well as the beetles, were established on all the purse worlds. Other known native species include: