The known world is composed of at least three continents (Westeros, Essos, and Sothoryos), a large landmass (Ulthos), and a number of many smaller islands. None of the four major landmasses have been completely mapped, and much of the world remains unexplored. While the maesters of Westeros know a good deal about the lands to the far east, distance is still an issue, and past a certain point myths and legends become a factor in their records.
The known world is part of a round planet, which might be a little larger than Earth. There might still be smallfolk who believe the world to be flat. On the whole, however, wise men and scholars from various civilizations (Valyria, Qarth, Yi Ti, and the maesters of Westeros) have known for centuries that the world is a round globe. Based on observations from astronomy, these scholars each determined that the only way the motion of the stars makes sense is if the world is round. It is therefore understood that it is possible, in principle, for a ship to circumnavigate the globe, but despite the efforts of several explorers, no one has ever succeeded in the attempt.
The maesters of the Citadel have speculated on the age of the world. According to Archmaester Perestan, the world is forty thousand years old, and Archmaester Mollos instead suggests five hundred thousand years, while Maester Yandel asks whether it might be older than either figure, and points out that no accounts of its beginnings exist, as its origins predate written history, meaning that no-one can know for certain.
The Known World
Located in the far west of the known world, the continent of Westeros is long and relatively narrow, extending from Dorne in the south to the Lands of Always Winter in the far north. The Wall, the border between the Seven Kingdoms and lands beyond the Wall to the north, is 300 miles long, indicating that Westeros is roughly 900 miles wide at its widest point, east to west. North of the Wall, much land remains uncharted.
Westeros contains the Seven Kingdoms south of the Wall, and the Lands of Always Winter north of the Wall. The Seven Kingdoms, first unified under Targaryen rule, are made out of nine regions (the crownlands, Dorne, the Iron Islands, the north, the Reach, the riverlands, the stormlands, the Vale of Arryn, and the westerlands). Bordering on Westeros lie the Sunset Sea (to the south), the narrow sea (to the east, southern half), and the Shivering Sea (to the east, northern half).
Separated from Westeros by the narrow sea, Essos extends eastwards for many thousands of miles. It is larger than Westeros, but much of it consists of less densely populated steppes, plains and deserts. The western edge of the continent is controlled by the nine Free Cities, while the city-states of Slaver's Bay are in the south-central region. Much of the continental interior, known as the Dothraki sea, is grassland ruled by the tribal warriors known as the Dothraki. Further east is Qarth and the fabled Jade Sea. The mapped lands of Essos are divided by the Bone Mountains, which run from the Shivering Sea in the north to the Jade Gates in the south. East of the Bone Mountains are the Plains of the Jogos Nhai, Yi Ti, the Grey Waste, Mossovy, and the legendary Asshai in the foreboding Shadow Lands.
Sothoryos, also written as Sothoros, is south of Essos, on the far side of the Summer Sea. It is a large continent, perhaps as long as Essos is wide, consisting of deserts and jungles and mountains. It is said to be a haven for plagues and dangerous animals, and has not been explored much by Westerosi beyond the northern coastal regions. (The Summer Islanders may have mapped the continent and its coastlines, but they do not share their knowledge.) Off the coast of northwestern Sothoryos are the Basilisk Isles, and to the west is Naath.
Ulthos is a large landmass to the southeast of Essos, across the Saffron Straits from the Shadow Lands. It may or may not be a continent, and its size is still unknown, as it is on the edge of the known world.
The largest island in the known world is Great Moraq, between the Summer Sea and the Jade Sea to the south of Qarth. The second largest appears to be Ib in the Shivering Sea north of the Kingdoms of the Ifeqevron, followed by the largest of the Summer Isles, Jhala. See also various other islands.
The largest seas appear to be the Shivering Sea, north of Essos, and the Sunset Sea, west of Westeros. The Summer Sea and Jade Sea lie between Essos and Sothoryos, and the narrow sea separates Westeros from Essos.
Most scholars do agree that because the world is round, it is theoretically possible to sail west from Westeros across the Sunset Sea and eventually come around to Yi Ti in the far east, but no one has ever succeeded in the attempt. There are basically three theories as to the size of the Sunset Sea: most believe that it is an ocean so vast that no ship could ever make the entire voyage to Yi Ti without running out of supplies, while a few explorers dare hope that it is just large enough for ships to successfully complete the trip (if they can find safe passage, though none ever have). A very rare few have posed the controversial question that the Sunset Sea might be so vast that there are actually entirely new, undiscovered continents between Westeros and Yi Ti. George R. R. Martin has stated that he is not sure if counterparts of the Americas or Antarctica or Australia exist in the known world.
Alys Westhill and Eustace Hightower's expedition of 56 AC discovered Aegon, Rhaenys, and Visenya, three small islands in the Sunset Sea, southwest of Oldtown, that are further west than the Lonely Light. While Eustace turned back to return to Westeros, Alys continued sailing west, and was never seen again.
Lord Gylbert Farwynd of the Lonely Light, the westernmost of the Iron Islands, speaks of lands farther to the west, across the Sunset Sea. According to him, this land has no winter and no death. These claims are not treated seriously.
Maesters have heard that explorers from the Summer Isles may have mapped the western coasts of Sothoryos to the bottom of the world. The explorers also may have discovered strange lands far to the south, and west across the Sunset Sea. However, the truth of these stories is known only to the princes of the isles and their captains.
It has long been accepted amongst the wise that our world is round. If this is true, it ought to be possible to sail over the top of the world and down its far side, and there discover lands and seas undreamed of. Over the centuries, many a bold mariner has sought to find a way through the ice to whatever lies beyond. Most, alas, have perished in the attempt, or returned south again half-frozen and much chastened.—Maester Yandel
Maester Nicol’s The Measure of the Days — otherwise a laudable work containing much of use — seems influenced by this argument. Based upon his work on the movement of stars in the firmament, Nicol argues unconvincingly that the seasons might once have been of a regular length, determined solely by the way in which the globe faces the sun in its heavenly course. The notion behind it seems true enough—that the lengthening and shortening of days, if more regular, would have led to more regular seasons—but he could find no evidence that such was ever the case beyond the most ancient of tales.—Maester Yandel
Wiser men suggest that somewhere beyond the waters we know, east becomes west, and the Shivering Sea must surely join the Sunset Sea, if indeed the world is round.—Maester Yandel
Behind the Scenes
You will find a map of the "known world" in THE LANDS OF ICE AND FIRE... one that includes lands and seas you have never seen on any of my maps before. [...] Even so, it's not a COMPLETE world map, no. The idea was to do something representing the lands and seas of which, say, a maester of the Citadel might be aware... and while the maesters know more about Asshai and the lands beyond than a medieval monk knew about Cathay, distance remains a factor, and past a certain point legends and myths will creep here. Here there be winged men, and such. [...] These are very nice maps, I hope you will agree. Huge and beautiful, and while they DON'T show the whole world (sorry, no, you're not going to get the Westerosi equivalent of the Americas or Antarctica or Australia, assuming such places exist), you will get a glimpse of distant lands where my characters (and thus the novels) will likely never go.
EW: This may be a silly question, but: When you think of the world you’ve created, where seasons last for years, where is it? It is another planet?
GRRM: It’s what Tolkien wrote was “the secondary world.” It’s not another planet. It’s Earth. But it’s not our Earth. If you wanted to do a science fiction approach, you could call it an alternate world, but that sounds too science fictional. [...] I have people constantly writing me with science fiction theories about the seasons — “It’s a double star system with a black dwarf and that would explain–” It’s fantasy, man, it’s magic.
- The Lands of Ice and Fire, a collection of official maps of the world of A Song of Ice and Fire
- World Map (HBO Game Of Thrones), a map of the known world for the HBO Series Game of Thrones
- Geography Portal
- A Game of Thrones, Chapter 64, Daenerys VIII.
- The World of Ice & Fire, The Reign of the Dragons: The Conquest.
- The Lands of Ice and Fire, The Known World.
- Not A Blog: Maps! Maps!! Maps!!! (Oct. 30th, 2012)
- So Spake Martin, Euron and the Globe (March 21, 2002)
- So Spake Martin: Trade with Asshai (August 26, 2000)
- The World of Ice & Fire, The Targaryen Kings: Jaehaerys I.
- Fire & Blood, The Long Reign - Jaehaerys and Alysanne - Policy, Progeny, and Pain.
- Fire & Blood, Heirs of the Dragon - A Question of Succession.
- A Feast for Crows, Prologue.
- The World of Ice & Fire, The Dawn Age.
- A Game of Thrones, Chapter 21, Tyrion III.
- The Lands of Ice and Fire, Westeros.
- The Lands of Ice and Fire, Beyond the Wall.
- The World of Ice & Fire, Beyond the Free Cities: Sothoryos.
- The World of Ice & Fire, Beyond the Free Cities: The Summer Isles.
- Not A Blog: Winter is Coming... (November 15, 2012)
- A Feast for Crows, Chapter 19, The Drowned Man.
- A Game of Thrones, Chapter 66, Bran VII.
- The World of Ice & Fire, Beyond the Free Cities: The Shivering Sea.
- The World of Ice & Fire, Ancient History: The Long Night.
- The World of Ice & Fire, Beyond the Free Cities: East of Ib.
- Entertainment Weekly: George R.R. Martin talks 'A Dance With Dragons'