The Xindi are unique in that the "race" is comprised of six distinct species. These share the same genetic origins but have developed along very distinct lines; aquatics, avians, insectoids, primates, reptillians, and sloths. The Xindi terms for their species have not yet been revealed. All Xindi, regardless of species, share characteristic ridges on their cheekbones.
Various Xindi were involved in a war lasting about 100 years that ended with the destruction of their homeworld, leaving an asteroid field in its place. The Insectoids and Reptillians planted devices that triggered the catastrophe.
The Xindi appear to be pawns in the Temporal Cold War, as they were supposedly informed circa 2152 that they would be victims of a devastating attack from humanity in the 2500s. The Xindi council launched a premptive strike on Earth as a precursor to a genocidal second attack. The Xindi spent the early part of 2153 deciding how to confront the threat of Humanity and planned a biological weapon based on the Human genetic profile.
Thought to be extinct since the destruction of the homeworld.