The Red Waste is an extensive area of desert and wasteland in Essos. It is located east of Slaver's Bay and Lhazar, and south of the Dothraki Sea. Its southern edge runs along the Summer Sea, whilst to the west lie the Bone Mountains.
The Red Waste is quite large, stretching from north to south for approximately 800 miles, and from east to west for roughly 600 miles. The Red Waste is arid and parched, with no rivers or sources of water other than a few viable wells, located in the ruins of abandoned cities.
The ruined cities of Vaes Orvik, Vaes Tolorro, Vaes Shirosi and Vaes Qosar are located in the Red Waste, all fairly close to its southern edge. The populated cities of Port Yhos, Qarkash and Qarth are located along the south coast of the Red Waste. These cities have survived as sea travel brings them food and supplies, whilst the Waste forms a convenient protective barrier against attacks from the Dothraki to the north.
The Red Waste does not appear to have always been so large. It was once considerably smaller, and over time expanded, swallowing the settled cities as it did so. The inhabitants of those cities were forced to flee to other lands. The reason for this expansion of the wasteland is not known.
Daenerys and her retinue push through the Red Waste, travelling for weeks on end. Some of Daenerys's followers, such as Doreah, die during this harsh journey. They eventually find shelter in the ruins of Vaes Tolorro. Thanks to the wells in the city, which are still viable, and some hardy fruit groves, they are able to recover whilst Daenerys's bloodriders explore the surrounding area. Once the route to Qarth is revealed, Daenerys and her followers depart the Red Waste.