Me! i have most of my essay written but i can't figure out how to say this in different words but with the same idea. it sounds pretty easy but i am just stressed out and i can't figure it out. here are the sentences: mesopotamian and indus river valley priests were referred as has head officials who had vast amounts of authority in these two civilizations primitive forms of democracy. religion shaped the structure and social caste of the four river valley civilizations. 

Most of it sounds pretty good. Maybe reword it like this if you're wanting to switch it up. Like I said, it sounds pretty good as you have it though.

Religion shaped the structure and social caste of the four River Valley Civilizations because the Mesopotamian and Indus River Valley priests held vast amounts of authority and were considered to be head officials of the civilizations' primitive forms of Democracy.

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.