B. geographical boundaries created in earlier historical periods
The main factor was the utilization of raised field agriculture. They would build these fields that had been artificially raised to a certain height along a flowing water source (mostly rivers but occasionally streams as well in some cases). When tropical weather patterns would cause said water sources to flood, instead of washing away the crops, it would act as irrigation for the raised fields. Securing a steady food source allowed the Mayans to support a large civilization in the tropical regions they called home.
Answer: Wealthy civilizations conquered neighboring areas.
Explanation:
Land has always been a valuable resource and in the ancient world was a sign of how much power a nation possessed.
With the wealth accumulated by the wealthier civilizations, they were better able to not only raise armies but to equip them as well.
They would then use these armies to conquer neighbouring areas to increase their influence and area of control and to show how powerful they were.
In the days before World War II, all three countries were colonies/territories of other countries.
The Philippines was an American Territory.
Vietnam was a French Colony.
India was a British Colony.
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