How was the grand canal central to the reunification of china in the 7th century and to its continued development through the 12th century?

The Grand Canal was key to China's reunification as it linked both its huge waterways to irrigate and drain China's agricultural zones. Thanks to this, which represented the longest waterway made by man, China's agricultural system prospered, and the population in agricultural areas has grown. Ships with provisions navigated through the canal, boosting the creation of huge urban areas next to its shores, which otherwise would have not been able to receive supplies with such ease.

first paragraph (and busy all the night ,with a silence deep and white )

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