Here is the full list of all 50 Grand Ages: Medieval achievements.
4 towns taken over
Campaign: Barnas Goes Nuts
You have plundered 50 traders.
2 towns taken over
You have plundered 10 traders.
You have declared war.
You have built 10,000 km of roads.
You have slain 5 predators.
12 towns founded
You have built 500 businesses.
You have built 1,000 km of roads.
You have unlocked an entire tree in the development diagram.
A town has reached 3,000 inhabitants
You have amassed 5,000,000 gold.
You have unlocked all commodities.
You have built 200 businesses.
8 towns founded
4 towns founded
Campaign: In bed with Eudokia
You have discovered 50 Adventure Sites.
You have discovered 10 Adventure Sites.
You have maximized the experience of a military troop.
One of your towns or cities has achieved the maximum level of prosperity.
You have traded 1,000,000 barrels of commodities.
You have entered into your first trade agreement.
You have built 50 businesses.
You have traded 10,000 barrels of commodities.
6 towns taken over
Out of all your competitors, you founded the most towns upon reaching the rank of
5 towns taken over by diplomatic means
5 towns taken over by military means
A town has reached 8,000 inhabitants
A town has reached 15,000 inhabitants
Out of all your competitors, you had the largest town or city upon reaching the rank of
Out of all your competitors, you built the most businesses upon reaching the rank of
You have celebrated your first festival.
You have amassed 50,000,000 gold.
You have recruited 100 troops in the game.
You have destroyed 5 bandit camps.
You have built 10 defense towers.
You have eliminated a competitor.
Campaign: You have completed the campaign
Finished first multiplayer game
Won first multiplayer game
Handed goods over to a fellow player
Snuffed out a fellow player's troop
Took over a fellow player's town
Recruited a troop of knights
You have 50 units of military troops under your command
You have built your first ship