So, I'm taking notes from my AP World History textbook, and something I notice is the following few sentences.
In nonurban societies almost everyone engaged in the basic tasks of subsistence, gathering or growing enough food to feed themselves and their families. Cities, however, depended on villagers to produce surplus food to feed urban residents who did not engage in food production but, instead, specialized in activities such as metallurgy (creating useful objects from metal), crafts, administration, and serving the gods. In Mesopotamia, a city controlled the agricultural land and villages in its vicinity, requiring surplus foodstuffs to feed its population of specialists. In return, the city provided rural districts with military protection against bandits and raiders and a market where villagers could trade surplus products for manufactured goods produced by urban specialists.
Presumably, the early Society Stage will be a lot like ancient civilizations like Mesopotamia, with Society Centers populated by non-laborer specialists like Artisans. Now, based on the above paragraph, there are two ways of comparing it to Thrive. Either expansion will begin rather early in a way similar to spice nodes in Spore (except with smaller SC's being absorbed), or interaction and diplomacy will begin rather early (with the smaller SC's being AI trading partners). The latter could become the former if a diplomacy option is "merge with us and we'll protect you."
Just a quick thought... I need to get back to work.