essos

Essos is an immense landmass located to the east of Westeros, extending into the far east of the known world. The Free Cities are located on its north-western shores, with the Dothraki Sea located deep in the continental interior and the cities of Slaver's Bay on the south coast. The continent extends far to the east, around the Jade Sea, to the distant and fabled lands of Asshai and the Shadow. Essos climate is temperate in the northern and western portions, and subtropical in the southern & eastern portions. Rainfall generally decreases as one moves eastward in Essos.

The extreme eastern end of the continent has not been fully mapped. Westeros's landmass is much longer from north to south, extending from the deserts of Dorne to the polar regions north of the Wall, but east-to-west travel is much shorter. In contrast, the greater bulk of Essos runs along an east-west latitude, while its northern and southern extremes are a shorter distance. On the western shore of Essos, the furthest point north at Braavos is at the same latitude as the Vale of Arryn, and the furthest point south near Tyrosh is at the same latitude as Dorne, separated only by the island chain known as the Stepstones. Pentos, located roughly between these two extremes, is at the same latitude as the Westerosi capital of King's Landing.

People or things from Essos are referred to as "Esossi". Unlike Westeros, Essos is not controlled by a single political entity. Instead its different regions are controlled by a mixture of city-states, nomadic tribes and a few small kingdoms.

The regions shown in the series are:

Twelve thousand years ago, Essos and Westeros were linked by a land bridge, the Arm of Dorne. When the First Men crossed the Arm and invaded Westeros with weapons of bronze, they were opposed by the Children of the Forest. When they could not stem the invasion, the Children destroyed the Arm with sorcery, creating the Stepstones.

Four thousand years later, the Children and the First Men united to defeat the White Walkers in the War for the Dawn. Although this war was fought predominantly in Westeros, it became part of Essosi legend when a great hero, Azor Ahai, helped defeat the undead using a sword called Lightbringer. This act became instrumental in the myths of the faith of the Lord of Light.

According to tradition, more than six thousand years ago the Faith of the Seven appeared to a warlord of north-western Essos. They inspired Hugor of the Hill to conquer the surrounding region and forge the realm of Andalos. Some centuries later, the Andals chose to cross the Narrow Sea and invade Westeros, landing along the coast of the Vale of Arryn. They overran Westeros over a period of centuries, eventually coming to dominate most of the southern half of the continent.

Five thousand years ago the Ghiscari Empire was the dominant power of south-central Essos. Shepherds living peacefully on the Valyrian Peninsula discovered  dragons lairing in the Fourteen Fires, a chain of large volcanoes stretching across the neck of the peninsula. Possibly using sorcery, the Valyrians tamed these dragons and began riding them, using them in war. The Valyrians fought five great wars against Ghis, eventually destroying the capital city of Old Ghis and bringing about the downfall of the Ghiscari Empire. The Valyrians began expanding in their own right, inheriting the lands of the old Ghiscari Empire and establishing their own colonies, the first of which was at Volantis.

One thousand years ago the Valyrians made war upon the Rhoynar, destroying their cities with dragonfire. The Rhoynar fled by sea, escaping to Dorne in Westeros. The Valyrians overran western Essos, establishing eight colony-states along the coast and in the rich hills and forests of the north. Following this the Valyrian Freehold was destroyed in a single night of fire and chaos. The Fourteen Fires erupted, destroying the Valyrian Peninsula and raining fire down on all the lands of Valyria. Almost all of the Valyrian dragons were destroyed. Most of the Valyrian nobility was wiped out, save only for the rulers of the colony cities to the north-west and the Targaryens, a noble family living on the island of Dragonstone in the Narrow Sea. The cataclysmic event was aptly named the Doom of Valyria. For a century after the Doom, Volantis led the way in attempting to rebuild the Freehold, at one point seizing control of Myr and Lys for several decades. An attempt to take Tyrosh saw them overextend and they were defeated in a bloody war, losing all of their lands save Volantis itself. At the end of this period the Targaryens invaded Westeros with their dragons, uniting it under the rule of Aegon I Targaryen. Also during this period the Dothraki emerged from the east, beginning their rise to power that would see most of the former colonies cower before them. The exception was Qohor, which hired an army of Unsullied warrior-eunuchs who defeated the Dothraki in open battle. Following the fall of Valyria, the Ghiscari became more resurgent. They founded the city of New Ghis and proclaimed the rise of a new empire. However, the Ghiscari cities of Slaver's Bay refused to join this new nation and remained independent.

A century ago there was a bloody civil war in Westeros known as the First Blackfyre Rebellion. After the defeat of the rebels at the Battle of the Redgrass Field, their surviving leaders fled to Essos. Under the leadership of Aegor Rivers, better-known as "Bittersteel", they established a mercenary army known as the Golden Company, vowing to one day return him from exile. However, the fifth such attempt, the War of the Ninepenny Kings, ended in disaster. Their then-leader,  Maelys the Monstrous, was slain by Ser Barristan Selmy on the Stepstones, ending the male line of the Blackfyres. Since then the Golden Company has remained active in Essos, fighting for coin.

More recently Essos has been plunged into chaos by the rise to power of Daenerys Targaryen. The daughter of the Mad King of Westeros, Aerys II Targaryen, Daenerys was born on Dragonstone and taken into exile in the Free Cities when still a child. After years spent fruitlessly trying to raise support to retake the Iron Throne, Viserys and Daenerys were given sanctuary by Magister Illyrio Mopatis in the Free City of Pentos. 

For a more detailed history of Essos, visit here.