Which geographic feature did the british government use in 1763 as a boundary to restrict the westward settlement of American colonists?

In 1763, the British government established the Proclamation Line, which prohibited American colonists from settling west of the Appalachian Mountains. This boundary was intended to stabilize relations with Native American tribes and prevent further conflicts as settlers moved into new territories. The Proclamation was part of Britain’s efforts to manage its expanded territory after the French and Indian War.