Ans: In geology, the crust is the outermost solid shell of a rocky planet, dwarf planet, or natural satellite. It is usually distinguished from the underlying mantle by its chemical makeup; however, in the case of icy satellites, it may be distinguished based on its phase.
Mecca was an important City for Arabs on the Arabian Peninsula before Islam because it was A) A Major Port City.
After a long period of civilization, Ancient Egypt fell to the Persians after they invaded the place in 343 B.C. That was basically the end of the civilization altogether. When you hear about the Egyptians still existing after that time period, it means that the area is taken over by Persians, later Romans, and etc.