Which country has underground reservoirs of water that were discovered in the mid-1950s?

Africa

Explanation: Scientists say the notoriously dry continent of Africa is sitting on a vast reservoir of groundwater. They argue that the total volume of water in aquifers underground is 100 times the amount found on the surface.

after the roman empire, the catholic church began to unify by taking on many duties of a government.

explanation:

the addition to geographic boundaries that might have  kept the people of the huang river civilization from traveling to far distance region is that they had learned about the other river valley civilizations but feared contact would bring invasion.

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