Westeros is a continent located in the far west of the known world. It is separated from the continent of Essos by a strip of water known as the Narrow Sea.
Almost the entire continent, barring only the lands in the furthest north beyond the Wall, is ruled by a single political entity known as the Seven Kingdoms, which holds fealty to the King of the Andals and the First Men, who sits on the Iron Throne in the city of King's Landing. The terms "Seven Kingdoms" and "Westeros" are normally used interchangeably.
People or things from Westeros are referred to as "Westerosi".
Twelve thousand years ago, Westeros was inhabited by the diminutive Children of the Forest, a nonhuman race who lived in peace and harmony with nature, worshipping the Old Gods of the Forest. The First Men, a human ethnic group, invaded Westeros across the Arm of Dorne, armed with weapons of bronze. In a significant military conflict, in which the Children allegedly destroyed the Arm of Dorne with magic (resulting in the Stepstone islands) and flooded the Neck, the two sides fought to a standstill and made a pact of friendship and alliance. The First Men adopted the worship of the old gods at this time.
Four thousand years later, Westeros was invaded by the White Walkers during a winter that lasted for a generation. In the War for the Dawn, they were defeated by an alliance of the First Men and the Children, though only at grievous cost. The Children disappeared from Westeros at this time. Brandon Stark, Bran the Builder, raised the Wall to bar the White Walkers from returning and founded the Night's Watch to guard it. He also built the castle of Winterfell and established House Stark as the ruling house of the Kingdom of the North. Two thousand years later, the Andals invaded Westeros from across the Narrow Sea, landing in the Vale and sweeping across the continent. The Andals conquered the southern half of the continent but failed to seize the North, being thrown back several times at the defensive chokepoint of Moat Cailin. A patchwork of numerous small Andal kingdoms took shape across the south, eventually coalescing into several larger nations.
A thousand years ago, the Rhoynar, the warrior-people of the upper Rhoyne (a river network on Essos), fell into warfare with the mighty Valyrian Freehold. The Valyrians destroyed the Rhoynar cities using dragons. Nymeria, warrior-queen of the Rhoynar, led her people across the Summer Sea in ten thousand ships to land in Dorne. Making alliance with Prince Mors Martell of Sunspear, Nymeria conquered the myriad small kingdoms and lordships of Dorne to establish a powerful, proud and independent kingdom.
Four centuries ago, Valyria was destroyed in a volcanic cataclysm, the Doom. A century later, the scions of House Targaryen, who ruled the Valyrian trading outpost on the island of Dragonstone, invaded Westeros with a small army and three dragons. Aegon the Conqueror accepted the fealty of six kingdoms, while several generations later his descendants were able to bring Dorne into the union through peaceful alliance, hence the term "Seven Kingdoms".
For centuries the Seven Kingdoms have been shaped by rebellion and war. However, through civil wars and the loss of their dragons to time and conflict, the Targaryens ruled the entire continent (bar the lands beyond the Wall) for over 280 years until the actions of the Mad King, Aerys II, triggered the civil war known as Robert's Rebellion. At the end of this civil war, Aerys II and most of his family were slain and his surviving children fled into exile in the Free Cities. Robert Baratheon took the throne and at the start of the series has ruled for seventeen years.
The Seven Kingdoms are divided into nine administrative regions, seven of which were former independent kingdoms before the Targaryen Conquest. Each region, except the Crownlands, is ruled by a Great House, who in turn are commanded by the King on the Iron Throne. These regions are:
Ruled by House Stark from the castle of Winterfell. Bastards born in the North take the surname "Snow". The principal port and city of the North is White Harbor. The North is the largest of the regions of Westeros but also the most sparsely-populated, due the harshness of the long winter. The North also includes the Wall and the lands administered by the Night's Watch, which are technically independent but are almost always thought of in conjunction with the North.
Ruled by House Arryn from the castle known as the Eyrie. Bastards born in the Vale take the surname "Stone". The principal port and city of the Vale is Gulltown. The Vale is dominated and mostly covered by the Mountains of the Moon and its offshoot chains. Its borders are prowled by hostile hill tribes.
Ruled by House Tully from the castle of Riverrun. Bastards born in the Riverlands take the surname "Rivers". The principal ports of the Riverlands are Seagard, Saltpans and Maidenpool. Notable towns include Stoney Sept. The Riverlands are dominated by the mighty River Trident and its numerous tributaries, including the Tumblestone. The Riverlands, lying close to the center of the continent, have been the site for battles and conflicts throughout the history of Westeros. Once an independent kingdom, they were overrun by the ironborn a century before Aegon's invasion and are thus not counted as an eighth kingdom, despite their significant size and population. The Riverlands are, as their name suggests, one of the most fertile and populous regions in Westeros, which is in many ways the only reason they have been consistently able to recover from the frequent wars that cross their borders.
Ruled by House Lannister from the castle of Casterly Rock. Bastards born in the Westerlands take the surname "Hill". The principal city and port of the Westerlands is Lannisport. The Westerlands are noted for their hills and low mountains which are rich in silver and gold, providing House Lannister and their vassals with immense wealth.
Ruled directly by the King on the Iron Throne from the city of King's Landing, the largest city in Westeros and the capital of the Seven Kingdoms. Bastards born in the Crownlands take the surname "Waters". Other notable townships of the Crownlands include Duskendale and Rosby. The Crownlands stretch along the shores of Blackwater Bay and also across several islands in the Narrow Sea, such as Dragonstone, Driftmark and Claw Isle. The islands are separately administered from Dragonstone.
Ruled by House Baratheon from the castle of Storm's End. Bastards born in the Stormlands take the surname "Storm". The Stormlands include several offshore islands, most notably Estermont and Tarth. It ranks moderately among the other regions in terms of population and wealth. The Stormlands are wracked by frequent storms off the Narrow Sea, and experience significant rainfall. The Stormlands are also one of the most densely wooded areas in Westeros, particularly south of the Neck. It contains not only the Rainwood (which covers the southern half of the Stormlands), but also shares much of the Kingswood (spilling across the northern border with the Crownlands). As a result, its climate is in general that of a temperate rainforest.
Ruled by House Tyrell from the castle of Highgarden. Bastards born in the Reach take the surname "Flowers". The principal city and port of the Reach is Oldtown, the second-largest city of Westeros. The Reach is the second-largest region of Westeros and by far the most fertile and populous, allowing the Tyrells to field vast armies and also results in them being wealthier than any other family but the Lannisters. The Reach also includes several offshore islands, such as the Shield Islands and the Arbor.
Ruled by House Martell from the castle of Sunspear. Bastards born in Dorne take the surname "Sand". The principal ports of Dorne are Sunspear itself and the Planky Town at the mouth of the Greenblood. The people of Dorne are isolated from the rest of Westeros by the Sea of Dorne and the Red Mountains, giving them a greater sense of national identity than most of the other peoples of the Seven Kingdoms, even more than the ironborn and the Northmen. Since Robert's Rebellion and the murder of several prominent Dornish nobles during the Sack of King's Landing, the Dornish have pursued a more isolationist path.
A vast, snow-covered wilderness independent from the Iron Throne and separated from the Seven Kingdoms by the Wall. It is inhabited by tribes of people known as wildlings, who often attempt to raid along the Bay of Seals or the Bay of Ice or climb over the Wall for the same purposes.
The population of Westeros extends into many millions, though a precise count has never been attempted. The major cities of the continent have populations in the hundreds of thousands, and each of the Great Houses can field a reasonably-well-equipped army in the tens of thousands. Due to its desert climate, Dorne has the smallest overall population. Due to their extremely small size, the Iron Islands are also among the least populated. The North has one of the smallest overall populations, and is the most sparsely-populated region, with huge regions of deserted wilderness extending between the major towns and holdfasts. Meanwhile, the prosperous and fertile Reach is the most heavily-populated, followed closely by the Riverlands. Westeros is overwhelmingly populated by humans, to the point that non-human sapient races are considered mythical. However, it is known that the enigmatic White Walkers have returned to the far north of Westeros.
There are several notable human ethnic groups currently extant in Westeros:
The First Men were the original human inhabitants of Westeros, who crossed the Arm of Dorne and fought with the Children of the Forest before making peace with them. Thousands of years later, the Andals invaded Westeros and displaced or conquered the First Men everywhere south of the Neck. As a result, the First Men are still the predominant ethnic group in the North, though six thousand years of intermarriage with Andal lords has blurred this somewhat.
The people who live beyond the Wall are call themselves the free folk (called wildlings by people south of the wall) and are not held to be subject to the Iron Throne. They are descended from those First Men who lived north of the Wall when it was constructed. The free folk are not a homogeneous single group, but consist of numerous different tribes, townsfolk, farmers, fisher-folk and warriors, who mostly spend more time fighting one another than the forces of the Seven Kingdoms. Occasionally, they are united under an over-chief known as the King-Beyond-the-Wall.
The majority of the population of Westeros are descended from the Andals who invaded the continent some six thousand years ago. The Andals consider themselves more civilized and cultured than the other peoples of Westeros.
The ironborn are a grouping resulting from the intermarriages between the First Men inhabitants of the Iron Islands and the Andals who invaded them. While ethnically similar to other regions in the south of Westeros, which also have mixed First Men and Andal ancestry, their isolated geography on a harsh and rocky group of islands separate from the mainland resulted in their culture developing very differently. Rejecting the worship of both the old gods and the Seven, they developed their own faith based around the Drowned God and their own culture which favors piracy, martial prowess, and reaving over farming and trading.
The people of Dorne are descended from the Rhoynar, the hardy warrior-folk of the eastern continent who settled in Dorne after being driven out of their homeland by the Valyrians, and then intermarried with the local Andals and First Men. The blood of the Rhoynar is thus intermingled in the Dornishmen; Rhoynar ethnicity is most strongly represented in those who live near the coasts and rivers, and weakest in Dornishmen who live in the interior mountains. They tend to be olive-skinned with dark curly hair. They have a reputation for being hot-headed and sexually liberal. Unlike the other Seven Kingdoms, they practice equal primogeniture.
The Children of the Forest are a legendary race who ruled Westeros for untold millennia before the arrival of the First Men. According to myth, they were diminutive, long-lived, and few in number, but were protected by the powerful magic of the greenseers and the martial prowess of their elite warriors, the wood dancers. They helped the First Men defeat the White Walkers and raise the Wall, but disappeared from Westeros after the Andal Invasion. Maesters of the Citadel today claim that the Children were myths and never truly existed.
The White Walkers are, according to legend, a race of ice-based creatures hailing from the extreme north. Eight thousand years ago, they invaded Westeros and brought cold, terror and death to both the First Men and the Children before they were defeated in the War for the Dawn. According to some, they were not destroyed, only defeated and have spent millennia since this time asleep. Again, these claims are met with extreme skepticism today.
According to the wildlings, giants still exist north of the Wall and have some contact with the wildling communities.