This article is about the religious concept, for the episode see "The Night Lands."
Daenerys in House

Daenerys with Khal Drogo in the House of the Undying.

The Night Lands (Dothraki: Rhaeshi Ajjalani[1]) is the land of the dead in the Dothraki belief system

For a Dothraki soul to enter the Night Lands to ride with his or her ancestors, the body must be burned in a funeral pyre.[2] It is a major insult to the dead to leave his or her body unburned.[3]

When Daenerys Targaryen sees her dead husband Drogo in the House of the Undying, she asks if she is joining him in the Night Lands.[4]