The native Americans, Europeans, and west Africa. Hope that helps
I assume "Muslim belief system" refers to Islam, the religion, not any specific social construct. There are a lot of inherent elements. One is monotheism: there is only 1 god. Another element is the 5 Pillars of Islam, which give guidance on how to live one's life. Hope this helps.
It’s difficult because since it was so long ago in history, Things are often to lose its texture and result in being somewhat mixed in with the environment around the site causing it to become harder to find by professionals who dedicate their life to finding that sorta stuff. Hopefully I helped
The three invaders are the Huns, Visigoth, and the Vandals.