I actually just recently learned about this lol. Here is the answer tho:
<span>because they discarded old traditions and then began new ones.</span>
"<span>Slavery was abolished in the United States" has nothing to do with the Dredd Scott case, which instead said that blacks had no standing in court because they were not citizens. </span>
A possible reason was the attacks on them by crusaders and mongols around the 11th and 12th centuries. Another reason could have been the Arab rulers removing taxes from non Muslims and doing other things that hurt there income.
Because the more you spread out the power, the less one person has. Therefore, the more people that have power, the tyrant will have less power.