There were three Treants who signed the first contract. Most trees are pretty stupid, even treants were normally seen as being wise from their years of existence, but stupid none the less, because they are slow of mind and body. However magic doesn’t care what other people think of you. A few treants who cared about the outside world more than others did created an order that wound up being called “those who watch”. This is a horrible translation, but than again treants don’t talk like us, rustling leaves, the whistle of wind through the air are alien to us.
This group studied a great many things and paid close attention to the world. In the end there were only three who could and would contribute to the contract. Even quite a few members of “those who watch” thought that the whole contract was putting a bandage over a sword gash.