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