Here is the full list of all 20 Middle Age Conquest achievements.
Have 100 Houses
Reach 100 K Army Power
Win A Fight
Finish The Third Age
Reach 50 K Army Power
Reach 10 K Army Power
Finish The Second Age
Get 100 Research Points
Have 50 Houses
Have 50 Gold Worker
Have 50 Wood Worker
Trade Any Resource For Another
Have 50 Food Worker
Lose A Fight
Go to War Once
Finish The First Age
Go Fightzone Once
Upgrade The Blacksmith For Once
Have 10 Houses
Let's Find A Chest Full of It