The fossil fuels formed hundreds of millions of years ago from the remains of is called

the mongolian invasion of china and central asia resulted in a disruption of the silk road as the chinese garrisons lost support from the chinese kingdoms which fell under the mongols. however, as the mongols established a formal dynasty in china, the successors of genghis khan restored the garrisons along the silk road allowing the safe travel caravans again.

- "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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