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