The Jade Sea is a large body of water in the far east of Essos, lies several thousand miles to the east of Westeros. Its western end connects to the Summer Sea at the straits of Qarth. Several major regions are touched by its shores: traveling east from Qarth, a ship will reach the great cities of Yi Ti, and beyond that, eventually reach the forbidding sorcerer-city of Asshai.
It is known as an exotic location and the source of valuable trade goods, such as rare spices and silks, but few men from Westeros ever travel east of Qarth to reach it. The trader's circle from Westeros to the Jade Sea and back is very long and dangerous, lasting two years round trip, and only the hardiest merchant ships dare to make the voyage. Even so, many traders (and smugglers) dream of saving up enough resources to make the trading circle around the Jade Sea, for while it is long, the profits from its successful completion will allow a merchant to live rich and comfortably for life.
Euron Greyjoy went raiding as far east as the distant Jade Sea. While there he lost his mind during a storm, and had to be tied to a mast to prevent him from jumping overboard. After the storm passed and he was released, Euron cut out the tongues of the entire crew - as he later glibly explained, because he needed silence.
In the books
In the A Song of Ice and Fire novels, the Jade Sea is connected to the Summer Sea by the Straits of Qarth, also called the Jade Gates. Qarth lies at the westernmost end of the sea, Yi Ti is in the middle of the northern short, and Asshai is to Yi Ti's southeast.
The southern extent of the Jade Sea is unknown: it is unclear whether the Jade Sea is a massive, landlocked bay connected to the Summer Sea (similar to the relationship between the Black Sea and the Mediterranean), or a totally distinct ocean which separates Essos from the southern continent of Sothoryos.
Traders from Westeros, the Free Cities and the Summer Islands are known to perform the "trader's circle" around the Jade Sea, stopping at every port to trade goods before taking them back to Westeros, usually via Slaver's Bay and Qarth. A single voyage to Asshai and back, performing the circle, can make a merchant crew rich, but it's also extremely hazardous. This kind of voyage can take two years or more.
The Lands of Ice and Fire, a collection of maps of the Song of Ice and Fire world, show that George R.R. Martin has radically reconceptualized the Jade Sea and its coastlands from what has appeared on the HBO maps (which are based on earlier drafts). In the new version, the Jade Sea now forms the southern coast of Essos, with Qarth located at the north-western edge of the sea rather than the south-western. A large island, Great Moraq, now separates the Summer Sea from the Jade Sea, with Qarth guarding the northern straits into the Jade Sea. There also exist southern straits (which run between the island and the continent of Sothoryos) into the Jade Sea, known as the Cinnamon Straits. A towering mountain range, the Bone Mountains, now separates the Dothraki Sea from unknown lands further east. Asshai is located at the eastern edge of the sea, roughly due south-east of Qarth and about as far from Qarth as Qarth is from Valyria.
Despite speculation that HBO would change its maps to match The Lands of Ice and Fire, the subsequently-airing seasons retained the same outline for Essos. This implies that the TV show and books have differing versions of the same continent, although since these lands are supposed to be mysterious and unknown to the Westerosi, it may be an intentional, albeit retroactive, in-universe error
The Further East of Essos
Jade Sea · Bone Mountains
Seas of the Known World
|Lesser and Inland Seas:|