Two main reasons why the great migration occurred

- "the most famous structure by far at saqqara is djoser's step pyramid. dating from the 3rd dynasty (2667—2448 bc), it was the first all-stone complex ever built on earth."

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the effect of the ming leaders banning ships with more than two masts was that there was no further construction of ships masts, because there was a surplus. ming emperors disallowed foreign exploration