Who formed the Great League of Peace and Power?

The correct answer is - The Six Nations of Iroquois speakers.

The Great League of Peace and Power was formed by the Six Nations of Iroquois speakers, and it was formed on the territory of what is now New York, with the purpose of it being that they manage to preserve good relations between their respective communities. Unfortunately, they were not able to safeguard and protect the alliance of Nations during the American Revolution, and were forced to take sides between the British and the Americans, in order to keep their independence and sovereignty.