The Guild of Sages is a small group of the oldest and wisest Turaga on the island. They are very reclusive, and rarely venture forth from the Great Library in Sakrinil. Their goals appear to be to amass as much knowledge as they can, and most would say they already have enough - one can learn almost anything they need to by speaking with them, if they have the coin (which will inevitably be put to finding out more information at a later date).
The Guild has existed since the islands beginning, long before the Justiciars took control and back when the island was first beginning. It was generally more accepting at that point, but have been far more defensive ever since a wing of the library was burned down almost ten thousand years ago.