What natural geographic boundary separates the colonies from unsettled territory?

The natural geographic boundary that separates the colonies from unsettled territory is physical boundaries such as mountain ranges, oceans, rivers and deserts. These are real natural line that separate two areas or different regions of the Earth.

Moreover, some examples of physical boundaries are the Rio Grande that separate United States and Mexico, while the Mississippi River form a large part of the boundary between Louisiana and Mississippi and Arkansas and Tennessee.

The answer is The characteristic geographic limit that isolates the provinces from agitated region is physical limits, for example, mountain ranges, seas, waterways and deserts.  

Explanation:

These are genuine regular line that different two zones or distinctive districts of the Earth.  Also, a few precedents of physical limits are the Rio Grande that different United States and Mexico, while the Mississippi River shape a vast piece of the limit among Louisiana and Mississippi and Arkansas and Tennessee.A district is a zone of land that has basic highlights. An area can be characterized by common or fake highlights. Dialect, government, or religion can characterize an area, as can timberland, untamed life, or atmosphere