A Buffer State is a relatively weak state lying between the borders of two or more rival or potentially hostile superior powers. Often, a buffer state is thought to avert conflict between the two.

A buffer state, sometimes, is a mutually agreed upon area lying between two greater antagonistic powers of comparable prospective. In that case, this area (buffer state) is usually demilitarized given that none of the two superior powers will host military forces there. Rather, the buffer state will likely have its own military forces.

If one of the powers surrounding a buffer state invades it, then often the result is a war between the superior powers.

For example, in the 19th century, Afghanistan acted as a buffer state as it lied with the then USSR to the North, British India to its South, China to its East, and the Persian empire to its West.