The western boundary for English land was the Mississippi River but the land between the Appalachian Mountains and the Mississippi River was reserved for Native Americans under the Proclamation of 1763.
Following the French-Indian War the Treaty of Paris 1763 awarded a large portion of French land to the English. Many of the colonists believed they would be allowed to enter into the new lands to settle but the British set a land barrier referred to as the Proclamation Line of 1763. This awarded and reserved land for the Native American tribes on the other side of the Appalachian Mountains. This would be one of the issues colonists would have moving forward toward the Revolution.