''The Mongol Empire'' campaign consists of 9 missions, you can play at any difficulty to unlock the achievement. I included videos for every mission of this campaign on hard difficulty to give you an idea how to beat them quickly and effectively.
The Mongol Empire Campaign (Longplay):1223: The Battle Of The Kalka River:1213: The Great Wall:1215: The Battle Of Zhongdu:1240: The Siege Of Kiev:1241: The Battle Of Liegnitz:1241: The Battle Of Mohi: 1267: The Song Fortress:1268: Blockade At Lumen Shan:1273: The Fall Of Xiangyang: