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