- "In the Shadow Lands beyond Asshai, they say there are fields of Ghost Grass, with stalks as pale as milk that glow in the night, murders all other grass. The Dothraki believe that one day, it'll cover everything, that's the way the world will end."
- ―Ser Jorah Mormont
On their travels east, Ser Jorah Mormont tells Daenerys that the Shadow Lands are said to be covered by "ghost grass", a form of grass that, in Dothraki belief, will overrun the green grass of the Dothraki Sea and spell the end of the world.
In the books
In the A Song of Ice and Fire novels, the Shadow Lands are a mountainous region beyond Asshai and one of the most remote locations of the Known World. The ruins of Stygai, "the city of night" are found at its heart. To go to Asshai is sometimes described as to "pass beneath the Shadow", though what exactly the Shadow is, or what is casting it, nobody seems to know.
The Lands of Ice and Fire map book (which features a significantly different outline of eastern Essos than the TV Series) revealed that the Shadow Lands form a large, triangular peninsula that juts out from mainland Essos into the Jade Sea. The tip of the peninsula points roughly southwest, with Asshai located at its narrowest point. The Ash River, which empties into the sea at Asshai, flows through the mountains of the Shadow Lands before reaching the city.
The Further East of Essos