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