In what ways were diverse people from the Arabian Peninsula through the Middle East, North Africa, and into Spain united? What held them together and unified them, and how was this done?

Answer 1

During which time period?

Answer 2

Your question is vague, as Ms. Sue notes, but I suspect this is what you're looking for:

http://en.wikipedia.org/wiki/Moors

Answer 3

It is around the 500 to 600 CE