There are many things one can infer from these civilizations just by
knowing that they were able to build such massive structures. One was
that they had a running civilization which was able to provide for its
citizens in adeqaute amount - this allowed them to be able to undertake
such feats.
Another thing is that we know they had the necessary
knowledge to actually build such structures - this tells us that they
were relatively advanced for their age and time.
Another thing
we can know from this is that they probably valued some sort of rituals
and had people who were at a higher level in society who also commanded
for these structures to be built.
Answer:
Believing that God had chosen him as his messenger Muhammad began to preach what God had revealed to him. The simple and clear-cut message of Islam, that there is no God but Allah, and that life should be lived in complete submission to the will of Allah, was attractive to many people, and they flocked to hear it.
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All able Muslims must make a pilgrimage (hajj) to Mecca at least once in their lifetimes.
This means that people will not follow that law specifically if it is ridiculous or discriminates against a group of people.
I think it is Earthquakes