Qarth is a great trading city located on the southern coast of Essos, on the straits linking the Summer Sea to the Jade Sea. Ships from Westeros, the Free Cities, the Summer Islands, and Slaver's Bay all pass through the Straits of Qarth on their way to the great trading cities of the Jade Sea, such as Yi Ti and Asshai.
Unlike most cities in Essos, Qarth has no fear of the Dothraki, as the forbidding and vast Red Waste divides it from the Dothraki sea. Nor was Qarth ever conquered by the old Valyrian Freehold. The Red Waste also separates Qarth from land-based travel with other parts of Essos, though it is a major port that conducts brisk maritime trade with major cities from Westeros to Asshai. Qarth seems to be located in an oasis, as the inside of the city is tropical, despite being surrounded by a desert.
Qarth is defended by immense stone walls and strong gates. The Qartheen have been known to bar entry to the city to those who do not meet their approval. Due to Qarth's isolation behind the Red Waste, being denied entry will often spell doom for travellers, and their bones can be found extending around its walls. This area is sometimes called the "Garden of Bones".
The people of Qarth are known as the Qartheen and call their home, "The greatest city that ever was or will be." Qarth is an oligarchy ruled by a council of nobles and merchants known as the Thirteen, most of which are members of the Pureborn, an aristocracy descending from the deposed Kings of Qarth. Although they rule by consensus, a member of the Thirteen can overrule the decision of the rest by invoking sumai, pledging their life and their blood to back up their decision.
Status is quite important among the Qartheen. They tend to be quite concerned about appearances, with men wearing vests which are covered in extravagant gold tracing and jewelry on the front. Women sometimes dye their hair to appear more exotic. Both men and women decorate their clothing with gold pieces shaped like insects and encrusted with jewels. Appearances, however, are not only a matter of status among the Qartheen, but also of survival, as, among the Thirteen for example, those who do not hold hereditary seats will keep them only for as long as they can appear wealthy and powerful before the eyes of the other twelve members and will be removed and replaced quickly if they fail to keep up appearances.
Doreah of Lys, a pleasure slave and handmaiden in the service of Daenerys Targaryen, relates a story she heard from a trader from Qarth who visited her brothel. The Qartheen man said that there used to be two moons, both dragon eggs. But, one of them strayed too close to the heat of the sun and cracked open, releasing a thousand dragons.
Daenerys Targaryen and her khalasar are dying of thirst in the Red Waste. She dispatches her three bloodriders in search of succor. Kovarro finds his way to the city of Qarth, located three days to the east, and guides Daenerys there. Outside she is greeted by the Thirteen, but when she refuses to show them her dragons they deny her entry. Xaro Xhoan Daxos overrides the decision of the council by invoking Sumai, an ancient Qartheen law, and takes Daenerys and her people under his protection.
Some time later, a group of the wealthy Qartheen attend a gathering at Xaro Xhoan Daxos' manse to get to know Daenerys.
Xaro Xhoan Daxos and Pyat Pree of the Warlocks of Qarth stage a coup in the city, assassinating the other members of the Thirteen and securing Daenerys's dragons for their own purpose, imprisoning them in the House of the Undying, the warlocks' tower. Daenerys later rescues her dragons, apparently killing Pyat Pree with dragonfire, before sealing Xaro Xhoan Daxos in his own vault - which turned out to be empty - as revenge for his subterfuge
While meeting with Razdal mo Eraz outside of Yunkai, Daenerys demands the release of every slave in the city or she and her army of Unsullied will take it by force. Highly offended, Eraz spits back that Yunkai is not Astapor or Qarth, and that the Yunkai'i have "powerful friends" who would take great pleasure in bringing Daenerys down.
Euron Greyjoy remarks that he has been raiding ships across the world oceans, so that "from Oldtown to Qarth, when men see my sails, they pray