Did you include a special rule in the game that increases unrest in Corsica unless the nations leader/emperor actually comes from Corsica?
Source: "Asterix en Corse" (Asterix in Corsica)
quote: « pour que les Corses acceptent un empereur, il faudra qu'il soit corse lui-même ».
(English translation: "that Corsicans will only accept an emperor if he's Corsican".