The Greet are an invertebrate xenos species that was annexed to the T'au Empire.
Their homeworld is a watery planet called Isla'su and located in the outskirts of the Fal'shia Sept.
After being discovered by the T'au Air Caste, the Water Caste extended them honourable greetings and invitations to join the T'au Empire, to ally themselves through the appeal of mutual protection, trade and technology.
The Greet allowed the Earth Caste to build many floating factories atop the surface of their planet-spanning oceans. This paid for the protection of their planet by orbital stations and allowed the Greet to better contribute to the Greater Good.
Canon conflict
In page 10 of Codex: Tau Empire (6th Edition), the Greet are stated to have been annexed during the First Sphere Expansion, but in page 28 this event is dated to 896.M40, during the Second Sphere Expansion. The first version is maintained in Codex: Tau Empire (7th Edition), but again Codex: T'au Empire (8th Edition) repeats the same conflict as the first book.
Sources
- Codex: Tau Empire (6th Edition), pp. 10, 21, 28.
- Codex: Tau Empire (8th Edition), pp. 12, 36.