Ulthos is the smallest, the least-known and most obscure of the known world's four continents. It is located south of Asshai and the Shadow Lands and east of Sothoryos. The continent forms the south-eastern coastline of the Jade Sea.
Only the extreme northern coast of Ulthos appears on maps and is almost entirely lacking in details, save for the existence of a large river emptying into the Jade Sea and a dense covering of dark forest covering much of the surrounding land.
The mapped portion of Ulthos stretches from the south-west to the north-east along the Saffron Straits for just over a thousand miles. The size of the remainder of the continent is not known.
- The existence of Ulthos was revealed in The Lands of Ice and Fire, a collection of canon maps of the Song of Ice and Fire world published in October 2012.
- Asked on his blog about Ulthos, George R.R. Martin said that it is a very large island, in the grey area between being a large island or a small continent.