What was the purpose of the proclamation line in 1763

The Treaty of 1763 ended the French and Indian War. After that, the British had to repay the Native Americans who helped them during the war. So, the Proclamation of 1763, gave the land between the Mississippi River and the Appalachian Mountains to the Native Americans. The Proclamation Line was the western border of the English colonies. Unfortunately, some colonists already lived past the lone and weren't going back. Also, the border was so long that it was very hard for the English to enforce. (not mine)

I’m pretty sure it’s 4, you can check on the calculator