The Tau are a young race of technologically oriented beings from the Eastern Fringe. T'au, the Tau home planet, was discovered in 789.M35 by the Adeptus Mechanicus ship Land's Vision. Adeptus Mechanicus records indicate that at that time the Tau species had mastered the use of simple tools and weapons, as well as fire. Before the planet could be cleansed and colonized by the Imperium however, a violent warp storm erupted around the planet. This continued for 6,000 years, making the Tau's homeworld utterly inaccesible.
It was not until the Damocles Crusade that the Imperium again contacted the Tau. The Imperium found the primitive Tau had advanced considerably. In six thousand years the Tau had advanced from spears and fire to colonizing planets and Pulse Rifles.