History of the Tau:

A long time ago (considering the 41st Millennium as the present day), the Tau Sept of Dal'yth had sent out a single fleet to search the Galaxy for more races which might be converted to the Greater Good, but once they had left the territory of the Tau Empire, they were never heard from again, until now.

This Tau fleet had returned as a group of traders, who often cooperate with the Imperium of Men, Eldar Craftworlds, even Orks & Dark Eldar from time to time. Their Earth Caste checks all the equipment they bring in & out, their Air Caste delivers it & secures the Fleet, their Water Caste are their most important asset, considering that they are the ones doing all the trading, while the Fire Caste acts as nothing more then a security force. For one reason or another, all their Ethereals had died, but they still know about the Greater Good & follow it, but they do not wish to force it toward others for it would ruin their trading connections.

What is also very notable about these Tau is that they work as Mercenaries when someone pays them wealthy enough, thus some Inquisitors had hired them on many occasions, making use of their hordes of Kroot allies & heavily modified equipment armed to the most battle-hardened & the most cunning warriors.

They are also known for making miraculous escapes when they get cornered, usually utilizing holograms, combined with intellectual tactics & plain luck.

The Roleplay:

The Tau fleet had approached an Imperial planet, it was a long voyage & everybody was happy that they found some solid ground & a chance to resupply, but they still needed to see if they have permission. They had sent a few Stealth Drones to the planet, to scout the situation, most of the Hive World was ruined & rivers of blood flooded the streets while a huge percentage of structures took severe damage, from bullets, grenades, bombs or otherwise. The Drones had taped it all & then returned to the main fleet, so Kor'O Dal'yth Sha'Ka could determine the best course of action. He figured that opening a communication channel with the Humans was the best course of action. And thus Por'El Dal'yth Kais was the one tasked to send this message:

-Human occupants, we Tau wish to aid you in your struggle one way or another, if you would give us permission to land safely, the Water Caste shall trade goods with you, the Air Caste shall aid your fleets, the Earth Caste shall repair your weapons, & the Fire Caste shall deal with any foe on land. I hope you accept this request, but if you decline, we shall leave ASAP. The choice is yours. Por'El, out.