various
The Tau Empire
Legends of the Dark Millennium (series)
The alien tau expand their empire and bring the Greater Good to the galaxy in this collection of tales that sees them come into conflict with the Imperium at every turn...
Warhammer 40k
anthology

It contains:
Out Caste
Fire And Ice
Farsight
A Sanctuary of Wyrms
Shadowsun: the Last of Kiru's Line
The Tau'va
Commander Shadow
The Kauyon
Aun'shi
The Patient Hunter

Also in:
Tales of the Greater Good