People who leave their countries because the land had been settled.
<h3>What is a frontier?</h3>
A frontier is the area of Land that is shared by two countries.
It is the border or outskirt of the country which can be occupied by people form the various country. People move here in war time or to search for greener pastures.
Therefore, People moved to the frontier because the land had been settled.
Learn more on frontier here,
brainly.com/question/24693743
