King George III issued the Proclamation of 1763. The Proclamation prevented the settlements of colonies in the west of the Appalachian Mountains. The goal of the Proclamation was to placate the Native Americans who did not side with King George III during the Seven Years' War.
The Native Americans had sided against the King under the leadership of Ottawa Chief Pontiac. The tensions between the British colonies and Indian tribes were so high, the British monarchy took the issue to King George III, resulting in the Proclamation of 1763.
Any land west of the Appalachian Mountains were reservations for the Native Americans. Any British colonist in that land had to relocate. Additionally, Native Americans had the ability to control the reservations under their law and cultural policies without British government interference.