The penultimate episode of Game of Thrones Season 7 sees Jon Snow and his gang of grumpy men venture North and battle White Walkers. The location isn’t just there to look cool, however — it has appeared on the show before and it’s crucial to its mythology.

As the Hound describes it, they fight near “a mountain that looks like an arrowhead.” In the episode, the group uses the mountain as a marker to indicate that they’re getting close to where they’ll find the Army of the Dead. That mountain also appeared in Season 6, when Bran Stark took a peek into the past and saw the Children of the Forest creating the Night King. In other words, that’s not just a funky mountain. It’s the White Walkers birthplace.

Their mythology has always been cloaked in shadow — although “Beyond the Wall” reveals that killing White Walkers also kills wights, their dead minions. (The White Walkers are the otherworldly blue beings while wights are simply reanimated dead bodies with blue eyes).

Season 4 also showed that they have some kind of headquarters with an ice structure — that’s where they turned Craster’s rejected baby boys into their own kind.

Although the ice structure didn’t appear in “Beyond the Wall,” presumably it’s near this mountain.

Here it is in Bran’s Season 6 flasback, in which the Children of the Forest create the White Walkers:

The children of the forest create the Night King in 'Game of Thrones' Season 6
The Children of the Forest at the Mountain in 'Game of Thrones' Season 6

And here it is in Season 7’s “Beyond the Wall.”

The mountain in 'Game of Thrones' Season 7

If the key to defeating the Army of the Dead is to take out the Night King, then perhaps this mountain plays an integral role too.

The Game of Thrones Season 7 finale airs on August 27, 2017.

Photos via HBO