The common geographic factor for Egypt and the fertile crescent were the big rivers, they made big alluvial deposits on their shores each year and allowed the people to have sufficient amount of food production. That opened the gates for civilizations to flourish in this places.
The Gambia is the smallest country in the region that is not an island or a series of islands.
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Answer:
The most common geographic boundary is the physical boundary.
Explanation:
Rivers, mountains, lakes, deserts are all physical boundaries.
The Mississippi River is a physical boundary between many countries that trespasses, including Iowa and Illinois, Louisiana, and Mississippi.
Pyrenees Mountains are also the geographic boundary between France and Italy.