"To accommodate for lack of dependable rainfall" would be the best option as to why the ancient Chinese organized large groups of people to build and maintain irrigation systems, since when rainfall would not come for long periods of time, the crops would likely die without proper irrigation.
Food ppl and giant things to move giant blocks of whatever like graint limestone<span />
<span>The great expansion of overseas trade during the 16th century, largely a result of voyages of discovery, favored the Atlantic coastal ports. A consequence was the decline of the trading cities of northern Italy.
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Hope i helped
The docking of America and Solviet Spacecraft.
The Electoral College elects the President