Why did cities begin to develop along the Tigris and Euphrates
Rivers?

The Tigris and Euphrates rivers provided water and ameans of transportation for the people who settled in the area. In ancient times, it was easier to travel by boat than over land. ... As the water spread over the floodplain, the soil it carried settled on the land. The fine soil deposited by rivers is called silt.

Explanation:

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regarding the law, the 15th amendment was specifically designed thinking in the rights of black free men.

even though ratified on february 3, 1870, the promise of the 15th amendment would not be fully applied for a long time.poll taxes and literacy tests would allow southern states disenfranchise african americans. only in 1965 the voting rights for african americans would be actually able to vote in the south.

in 1965, president johnson signed the voting rights act, which aimed to overcome legal barriers that prevented african americans from voting as it was guaranteed by the 15th amendment to the u.s. constitution.