Event triggered upon era change that narrates the transition between cultures. Could allow to pick between different bonuses, could simply be flavour, could trigger a temporary status on certain cities (depending on how much they support the new culture, like a stability hit or festivities).

This could help link up narratively the different cultures of an empire for the players.

Example: (Mycenaean -> Ach. Persian) "Following growing discontent, a new movement has emerged seeking to solve the current crisis. How did they seize power? CHOICE (all effects temporary): by Force [penalty to Stability, bonus to warriors & garrison], via Intrigue [bonus to stealth units], Peacefully [bonus stability, penalty to faith & gold] "

Transcendence might be treated differently (no event, or narrative event about foiling a coup).