Protecting Kobolds

Protecting kobolds
A large city tired of continious problems arising from its expansive sewers decided to solve its problems by making an alliance with a clan of kobolds. The kobolds set up traps in the sewers, and lived in them protecting them from any intruders and receiving help when they faced creatures too dangerous for them to handle. In return the clan received assistance from the cities wizards and clerics as will as weapons to use against its masters goblinoid enemies in the large subturanian caverns that riddle the world.
For thirty years this arrangement has worked well for both sides the city has received no trouble from its sewers and the Larger kobold clan has grown into a kingdom sending members to serve a year within the cities sewers. Bound by an oath and their lawful (though still evil) nature the kobolds will not dishonor the terms of their agreement. However they have recently uncovered a city of drow far from the human city one which is challenging their kingdom. They now need mercinaries to help them face down the drow and convince the dark elves that it is not worth the trouble of conquering the kobold nation.

I like to create rpg quest hooks that ally people with their natural enemies becuase I think that this creates an interesting conflict and a unique adventure. Planning battle strategy with kobolds for example.