From the passage we can understand that ------ .

Until recently, many archaeologists took the view that
civilized communities first arose in Egypt, though only
a very short time before a similar development In
Mesopotamia: a more recent opinion is now that the
earliest advances may have taken place in
Mesopotamia. Whichever view is followed, it is
necessary to bear in mind that geographical
conditions in both regions were not identical, and it
can in fact be stated that in Mesopotamia
environmental factors were not as wholly favourable
as In the valley of the Nile.