The Riverlands

The Riverlands is one of the constituent regions of the continent of Westeros. Located in the rough center of the continent, it has been a frequent battleground in the civil wars that have afflicted the Seven Kingdoms and also in the wars that took place between the old nations of the continent before the Targaryen conquest. During the time of the First Men, the Riverlands were an independent kingdom known as the Kingdom of the Rivers and the Hills.

The Riverlands were ruled by the ironborn at the time of the Targaryen conquest, and Aegon the Conqueror's assault was assisted by a popular uprising led by House Tully. For this reason - that the Riverlands didn't have a king at the time of the invasion - the Riverlands are not technically counted as one of the "Seven" Kingdoms (instead essentially making up the eighth "kingdom"). However, for administrative purposes, the Riverlands and their rulers are equal to any other region of the realm.

The Riverlands are ruled from the castle of Riverrun by House Tully. Bastards born in the Riverlands are given the surname Rivers.

Geography
The Riverlands are dominated by the watershed of the Trident River, so-called because of its three major tributaries - the Green Fork, the Blue Fork, and the Red Fork - which converge at Ruby Ford in the east. The Green Fork is the northernmost, running north-to-south almost up to the Neck near the entrance to the Stark-held North. The Green Fork is only traversable via the castle-bridge complex known as The Twins ruled by House Frey. Thus, large armies attempting to move into or out of the North are faced with only two, predictable choices: travel along the Kingsroad as it crosses the Ruby Ford to the east, or cross the Greek Fork at the Twins to the west, which requires paying an often steep toll to House Frey.

The Blue Fork is south of the Green Fork, and terminates near Seagard. The Red Fork is the southernmost and winds its way through the heart of the Riverlands, between the Red Fork and the God's Eye lake further south. After it passes Riverrun castle, the capital of the Riverlands, the Red Fork passes further to the south and west until it reaches the borders of the Westerlands held by House Lannister.

The Riverlands have a true temperate climate with warm summers and moderately cold winters, which increase in severity north of the Neck. Rainfall is moderate and adequate providing for the fertility of the region.

On the whole, the Riverlands possess few natural defenses or borders. They are bordered to the west and the east by mountains, but these are possessed by the Westerlands and the Vale of Arryn respectively. Rather, these are natural defenses that the Westerlands and Vale possess against the Riverlands. The extensive swamps of The Neck also form an effective natural barrier, but these are part of the North under the Starks, again more of a defense against invasion from the Riverlands than the other way around. The southern border of the Riverlands is more or less formed by the upper reaches of the Blackwater River, but this is not a particular impediment to travel between the Riverlands and The Reach to the south.

Castles

 * Riverrun, the seat of House Tully, the ruling house of the Riverlands. Located on the Red Fork of the Trident.
 * Harrenhal, the seat of House Whent, the largest castle in Westeros, held by some to be cursed. The castle is currently held by Lannister forces.
 * Raventree Hall, the seat of House Blackwood.
 * Seagard, the seat of House Mallister.
 * Stone Hedge, the seat of House Bracken.
 * The Twins, the seat of House Frey.
 * Pinkmaiden
 * Acorn Hall

Towns

 * Wendish Town
 * Stoney Sept
 * Maidenpool

Regions

 * Isle of Faces
 * High Heart
 * Whispering Wood

Coastal areas

 * Ironman's Bay

Lakes and rivers

 * The Trident
 * Blue fork
 * Red fork
 * Green fork
 * Gods Eye

In the books
In the Song of Ice and Fire novels, the Riverlands is relatively small in size but high in population. It is fertile due to the numerous rivers that run across its expanse, most notably the massive River Trident and its numerous tributaries.

The people of the Riverlands are known as 'rivermen' and are a mixture of hardy warriors, peaceful fisherfolk and devout smallfolk. The Riverlands possess a number of middling-to-large towns, such as Maidenpool, Saltpans, Fairmarket and Stoney Sept.

The borders of the Riverlands are held to be the marshes of the Neck in the far north, the Mountains of the Moon to the north-east, the Blackwater Rush to the south and the hills of the Westerlands to the west.

The Riverlands used to be a kingdom in its own right, but centuries before the Targaryen invasion they were overrun and conquered by the armies of the Storm King. The Storm King couldn't hold such a large territory, especially when the ironborn invaded in force from the west, and was forced to cede the Riverlands to King Hoare of the Iron Islands. The ironborn set about erecting a massive fortress on the lake known as the Gods Eye, completing it on the very day that Aegon the Conqueror set foot on the shores of Westeros. Aegon's dragons burned out the castle, Harrenhal, killing King Harren the Black. Lord Edmyn Tully of Riverrun led a popular rebellion of the river lords against the ironborn, helping Aegon drive them out. For this act, Aegon made House Tully the rulers of the Riverlands in his name.