Once a wandering tribe, your civilization now possesses a fine city where generations of families have settled and grown. Individuals are known by a single name alone, but with more and more citizens, it is becoming harder to track family lines, to know who is related to who. In order to better identify your people, you believe it is time for citizens of the same family to take a common second name. From where should the family name originate?
The identity of a newborn's mother is never a matter of dispute.
We should take the name from the father, a pillar of strength for the child.
We should let families be inspired by something from the world or myth.