Naraka

Naraka (ナラカ) is a town rumored to exist to the north of the Walls that is mentioned in the Attack on Titan: Before the Fall manga.

Shiganshina arc
When Kuklo is captured by the Shiganshina Military Police Brigade, he becomes acquainted with the young nobleman Cardina Baumeister, who tells him of the rumored town of Naraka. It is said that when the Military Police exiled criminals out of Shiganshina District into Titan territory beyond the Walls, some escaped to the far north where the Titans are least widespread and established a society there.

Cardina admits that it is unknown whether or not Naraka exists.

Trivia

 * "Naraka" is the name of a Buddhist concept of purgatory or hell, where souls must have their karma consumed until they can be reincarnated.