The destruction of the Xindi homeworld around the 2030s at the climax of a long civil war between its six sentient species, which wiped out the Avians and scattered the survivors.
Xindus was home to six intelligent species: Primates, Arboreals, Aquatics, Reptilians, Insectoids and Avians. A war between them lasted close to a century.
About 120 years before Enterprise entered the Delphic Expanse, the Insectoids and Reptilians set off enormous explosions beneath the planet's largest seismic fissures. The world broke apart, the Avians became extinct and the other five species were left without a home. The mysterious Guardians later exploited their search for a new world to turn them against humanity.
The disaster is described in the third season of Enterprise, first in The Xindi and then by the Arboreal Gralik in The Shipment, and the debris field is seen in The Xindi.