At the beginning of the game, staking out as large a territory as possible is desirable to many people. If you manage to start with a scout and find land bridge of one to two squares between certain areas CLAIM it!.
Very early in the game you can fortify your warrior or scout at this location and nothing can pass through. This effectively denies any civ from getting through to find building sites, other civs to communicate with and villages to plunder. You then become the gate keeper of whether to allow the civ communication with the other one or not.
a one land square bridge is a no brainer to block...
LLLLLL
xLLLxx
xxbxxx
xLLLx
LLLLLL
where L is land and x is water and b is the one square. Simply fortify your unit there and when you get a settler put it at that location. ANOTHER BENEFIT to this is that you now have essentially a canal through the continent, saving on distance when the game turns to naval operations.
