Boris Gudenuf
Deity
I think the key is to have some lesser city-like element to represent the non-urban populations, because is not just for hunter-gatherers, agrarian villages and pastorial camps were the core of what in game are "barbarians" and even most of CIVs playables were not urban at 4000BC.
Pastorial Camps were the more nomadic with regular migrations, but many Agrarian Villages also had massive migrations when some mix of natural and human presure forced them, a lot of civs on game would fit in these options.
Exactly. We need some kind of 'settlement' to represent both the earliest fixed human groups - originally gathered around really good food sources like fish and waterfowl-filled lakes and marshes and river bottoms, and later the smaller towns or Frontier Settlements that grabbed territory. Basically, 'semi-urban' concentrations that may or may not develop into true Cities later.
IF the game models any period before 4000 BCE, which I think is nearly a necessity to include Hunter-Gatherer Start, then there will automatically be some very serious early Climactic Events that can 'force' migration: the Lake Ojibwey drought in the Middle East, the drying up of the Sahara, the rising sea levels as the last of the glacial ice melted, etc. I've posted before that the early game could be designed to provide a series of really important decisions for the gamer: when or whether to settle down, how much to gamble on very early City Start, etc.