A shame, but I have a theory about this one:
Imagine you are at the remote outpost of Sealth, sending written word for contact with the East. The Great Chief was the obvious choice for the name of the settlement. As you are hurried sometimes in your communication, you, as may of us, tend to scribble a little at the end of a word as you are writing your cursive, causing the "h" to fall off a little. Then, the crossing of the "t" carrys into the preceding "l". The is causes the "lt" to look like "tt", and the loose end of the h makes it possible to be a "le".
Try it yourself: write "Sealth" quickly.