The Alps.
The Alps
You might protect your city-state from invaders by creating and maintaining a well-trained standing army. You might also create fortifications to block invaders.
In the past, the sea around Japan helped to protect them from invasion. However, after the USA developed the atom bomb, the difficulty of invading Japan influenced them to drop the atom bomb.
Oceans surrounding Japan protects it from invaders and provide plenty of fish.
to protect themselves from invaders
To protect china from invaders
To protect London from invaders.
The desert helped Egypt by giving them protection from invaders. :) :0
The British built forts mainly around their ports to protect the harbors from being bottled up by future invaders; such as at Singapore. The US also built forts around San Francisco Bay to protect it from future sea borne invaders (with Japan in mind, after the Russo-Japanese War 1904-1905).
hi
To protect china from invaders!