Having played a couple of MP games, it seems that certain continents/regions whatever are more likely to spawn barbs. In one game, I would clear a barb camp and it would immediately spawn another on the same continent. Meanwhile, my friend had zero barbs spawn around him. I must have cleared 8 barb camps so you expect at least some of those camps to spawn near him but nope ... always me. I'm not complaining though, I never have problems with barbs with the rare exception of pre-archery hose barbs and getting a bad roll on a coastal barb camp that spawns 3-4 quadremes.