The answer is: The sea
Back then, the techology that exist to travel by sea was not as developed as it is today. If an empire decided to travel through the sea in order to do some conquests, that empire will risk several things, such as:
- Loss in directions
- The ships could be swallowed by harsh wheather in the middle of the sea
- It need a lot of resources to maintain the armies during the travel
East Florida became a prime object of territorial ambition for President James Monroe and his Secretary of State John Quincy Adams. His secretary Adams was viewing opportunities to confront Spain for control of the region.
George Washington won the Battle At Yorktown and was responsible for the Continental Army.
Established when the Han Dynasty in China officially opened trade with the West in 130 B.C., the Silk Road routes remained in use until 1453 A.D., when the Ottoman Empire boycotted trade with China and closed them.
