OMG! This *finally* solves something that had confused me for a long time.Chance of a barb camp appearing on a given turn is weighted primarily by land tiles invisible to every civ (including city states) and secondarily by water tiles invisible to every civ (including city states). A land tile in fog of war is worth several water tiles in fog of war as far as the formula goes.
Should one be generated it will be placed on a land tile within fog of war.
What this means is that maps with very few water tiles (such as some of the regional scripts) see a barb camp respawn rate several times higher than the more standard maps.
The Frontier map often seemed to generate barbarian wastelands in the center of mountain-ridden landmasses where it became almost impossible for anyone to establish cities for a *long* time. I always wondered if the map type somehow had a special "spawn WAY more barbarians" variable hidden within it for some reason.
Well...that's one long-standing mystery solved. Thanks!