The original homeworld of the six Xindi species in the Delphic Expanse, torn apart at the end of a long civil war and leaving the survivors scattered across many colonies.
Xindus was the planet on which six intelligent Xindi species evolved side by side: Primates, Arboreals, Aquatics, Reptilians, Insectoids and Avians. Rivalry between them grew into a civil war that lasted close to a century.
As Degra's people explain during the third season of Enterprise, the war ended roughly 120 years before 2153, when the Reptilians and Insectoids set off massive explosions in the planet's seismic fissures. Xindus broke apart and the Avians died out with it.
Captain Archer finds only a debris field when he reaches the coordinates in The Xindi. The loss of the homeworld explains why the Xindi listen to the Sphere-Builders, who promise them a new one and warn that humanity will destroy it.