Here is the full list of all 35 Age of Civilizations II achievements.
Create 50 unions
Join 50 alliances
Form Australia-Hungary
Form Russian Empire
Form Japan
Create 50 vassals
Adopt the Horde ideology
Adopt the ideology of the City State
Create 25 unions
Create 20 vassals
Form Austrian Empire
Form Italy
Form Ottoman Empire
Adopt the ideology of Communism
Adopt Fascism ideology
Join 25 alliances
Join 10 alliances
Capture 1500 provinces
Create 10 unions
Adopt Republic ideology
Create 5 vassals
Capture 750 provinces
Adopt the Monarchy government
Create 5 unions
Capture 500 provinces
Join 5 alliances
Adopt the ideology of democracy
Capture 300 provinces
Create a vassal
Capture 150 provinces
Capture 75 provinces
Capture 30 provinces
Create union
Join alliance
Capture 10 provinces