Yi Ti is a nation and region in Essos located east of Qarth and the Bone Mountains and bordered by the Jade Sea to the south. Nearby islands in the Jade Sea are Leng and the Isle of Whips. North of Yi Ti are the Great Sand Sea, the Shrinking Sea, and the Bleeding Sea; a great river runs south from the Bleeding Sea through Yi Ti to the Jade Sea. Located east of Yi Ti are the Mountains of the Morn, the Shadow Lands, and Asshai. In the Common Tongue, things relating to Yi Ti are known as "YiTish".
The realm of the YiTish civilization is known as the Golden Empire of Yi Ti, which was, according to legend, preceded by the Great Empire of the Dawn. Maester Yandel speculates the YiTish civilization was contemporary with the realm of the Fisher Queens, whereas the YiTish priests insist that mankind's first towns and cities arose along the shores of the Jade Sea, dismissing the rival claims of the Sarnori and Ghiscari as the boasts of savages and children.
Lomas Longstrider called Yi Ti "the land of a thousand gods and a hundred princes, ruled by one god-emperor." The power of the God-Emperor has since fallen and extends no further than the walls of his own city, but the hundred princes rule their own realms as they see fit, as do the brigands, priest-kings, sorcerers, warlords, imperial generals, and tax collectors outside their domains.
The land of Yi Ti has thick, green patchwork farmland and a verdant rainforest. Rumors have it that basilisks roam the jungles of Yi Ti. Known cities in Yi Ti include Yin and Jinqi, along the Jade Sea coast, and Tiqui further to the north near the Great Sand Sea. The city of Asabhad is located at the western boundary of Yi Ti near the Bone Mountains and the Jade Gates. There is a trade route from Asabhad to Yin along the coast of the Jade Sea. The Five Forts guard the northeastern marches of the empire.
Yi Ti is ruled by a god-emperor, but true power may reside within the region's various princedoms. It has had various ancient capitals, including Tiqui. The Lion of Night is a god in Yi Ti. One of their major exports is saffron. Yi Ti is also known for its wine.
A Game of Thrones
Daenerys Targaryen remembers that basilisks infest the jungles of Yi Ti. In the Western Market of Vaes Dothrak Dany sees a fat cloth trader from Yi Ti haggling with a Pentoshi over the price of some green dye, the monkey tail on his hat swaying back and forth as he shakes his head. 
Before Khal Drogo's body is burnt on his funeral pyre Ser Jorah Mormont begs Daenerys Targaryen to come east with him, to Yi Ti, Qarth, the Jade Sea and Asshai-by-the-Shadow, to see all the wonders yet unseen. 
A Clash of Kings
In Qarth Xaro Xhoan Daxos tries to entreat Daenerys to accompany him on his pleasure barge to the Jade Sea. He suggests that they journey around Yi Ti to search for the dreaming city of poets and to sip the wine of wisdom from a dead man's skull.
A Storm of Swords
A Feast for Crows
A Dance with Dragons
- The Lands of Ice and Fire, The East.
- The World of Ice & Fire, Yi Ti.
- The World of Ice & Fire, Leng.
- The World of Ice & Fire, The Bones and Beyond.
- A Game of Thrones, Chapter 23, Daenerys III.
- George R. R. Martin's A World of Ice and Fire.
- A Clash of Kings, Chapter 40, Daenerys III.
- A Dance with Dragons, Chapter 1, Tyrion I.
- A Game of Thrones, Chapter 54, Daenerys VI.
- The World of Ice & Fire, Jaehaerys I.
- A Game of Thrones, Chapter 72, Daenerys X.
- A Storm of Swords, Chapter 71, Daenerys VI.
- A Feast for Crows, Chapter 21, The Queenmaker.