Crusader Kings II - Sword of Islam (DLC) Steam Key GLOBAL

Crusader Kings II is a game that has you answer the Pope's call for a Crusade. You will have to expand your domain and make sure your dynasty survives well after you're gone. To that end, you will have to secure income, appoint vassals, manage religious tension in your lands, put down the law and manage relations with a bunch of nobles, all while guarding your back from enemies known and unexpected.
The game can be started at any point between 1066 and 1337 and ends in 1453. How did the devs come up with 1337? Was the date historically significant, or did they just do it for the lulz? You might find out if you play the game.