Here you can buy the key Crusader Kings II Sunset Invasion DLC (addition to Crusader Kings 2) at a bargain price. After purchase, you will immediately receive a key, by activating which you will add DLC to the game Crusader Kings II to your steam account.

Without the original Crusader Kings 2 II game on your account, you cannot activate the Sunset Invasion DLC add-on.

https://store.steampowered.com/app/210902/Expansion__Crusader_Kings_II_Sunset_Invasion/

You can activate the key in any region.

Key activation instructions:
1. After purchase, you receive a unique key that you need to copy and enter into the Steam client.
2. Opens steam. We are looking for the button "Add game" in the lower left corner, then click on "Activate in steam"
3. In the appeared window, insert the format key - HHHHH-HHHHH-HHHHH
4. After activation, the game will appear in your library.