It is difficult to definitively say whether any given place or society is completely free from invaders. The possibility of invasion depends on many factors, including the geopolitical climate, the military strength and readiness of a country or region, and the intentions of other nations or groups. It is important for countries to maintain strong defensive capabilities and diplomatic relationships to help prevent invasion, but no place can be completely guaranteed to be free from the possibility of invasion or attack.
However, an invasion of powerful countries like China, Russia, or the USA would be near impossible, due to extremely protective defence systems and the threat of mutually assured destruction(MAD).
Have a Great Day!
~~~Harsha~~~