When ever they felt like it
When ever they felt like it
because they wanted to
to maintain "civilization" yes would be the answer. --civilization: a place with order.
Complex irrigation systems.
It has a humid subtropical climate
One major trend in early civilization and lifestyles was the organization of a complex institutional government and a definite social hierarchy.
to honor their rulers and please their gods
Mountain ranges & deserts
the rivers
the rivers
A highly complex culture is known as a civilization. For ex. Greece and Rome were civilizations because both were very complex during early years.
The Niger river