Sosaria is the name of a world of four continents that existed prior to the death of Mondain. It also may refer to the single continent (once known as the Lands of Lord British) after it became a world in its own right and before it came to be known as Britannia.
See also: History of Britannia
Before the land of Britannia came to exist in its modern incarnation, it was part of a greater realm known as Sosaria, a world consisting of four continents: the Lands of Lord British, the Lands of the Dark Unknown, the Lands of the Feudal Lords, and the Lands of Danger and Despair (which later became known as the Serpent Isle).
The First Age of Darkness
At some point in Sosarian history, a king known as Wolfgang was slain by Mondain, his second-born son. Mondain desired his brother's birthright and the powers of his father's magical Sun Ruby Gem, which had been promised him when he came of age. Using the gem's magic over the sun against itself, Mondain transformed the stone into the black Gem of Immortality, granting himself freedom from death and power over the minions of darkness.
Mondain's legacy had reverberations for over a thousand years. The undying wizard set the rulers of the land at odds with one another, and civil strife reigned in the eight kingdoms of the land while monsters of his devising roamed free upon the countryside. Mondain's alliances even extended to other worlds, putting the natives of Sosaria in contact with "starwalkers," alien creatures who assisted the sorcerer from the depths of space. It may be these "starwalking" creatures who were responsible for the influx of high technology into this age of Sosaria, as devices such as lasers and aircars were available at many locations during this era.
In Ultima I, an idealistic young king known as Lord British, envisioning a unified country, called out for a champion to put an end to Mondain. The Stranger appeared in response to this summons. The hero, after weathering numerous quests, eventually managed to travel back in time to the millennium before when Mondain first altered the ruby. The Stranger shattered the gem and slew Mondain, undoing the wizard's works.
After Mondain's defeat, however, Sosaria changed radically. For reasons unknown, the Lands of Danger and Despair, the Lands of the Dark Unknown and the Lands of the Feudal Lords disappeared from the landscape, wrenched from the world as though they never existed. While it was later found that the Lands of Danger and Despair could be accessed through the Serpent Pillars, the fate of the other two continents was unknown. The remaining continent, the Lands of Lord British, was still known as Sosaria.
The Second Age of Darkness
While Minax, Mondain's apprentice and lover, later sought vengeance for her paramour's death, most of what is known of her actions transpired on the Stranger's home world of Earth. She is still regarded historically, however, as a key figure in the Sosarian Age of Darkness, and folklore often speaks of her deeds as though they affected Sosaria.
The Third Age of Darkness and the Age of the Avatar
In Ultima III, the now much smaller Sosaria came under attack by the hellspawn Exodus, a daemonic machine-creature crafted by Mondain and Minax. Once more the Stranger was summoned by Lord British to deal with the threat to the realm. Following the defeat of Exodus, British began the unification of the Sosarian people under his system of Virtues, bringing in a Renaissance of learning and arts which culminated in the eventual Quest of the Avatar. At the festival which was held to commemorate the felling of Exodus, the land was rechristened as "Britannia." 
Some, however, objecting to the moral imperialism they saw in British's new Virtues, left the continent, eventually coming to settle in what was once the Lands of Danger and Despair, which for a time was known as "New Sosaria" before the name "Serpent Isle" was given to it, owing to the numerous strange ruins the colonists found there.
- The Lands of Danger and Despair
- The Lands of the Dark Unknown
- The Lands of the Feudal Lords
- The Lands of Lord British
Cities (at the time of Ultima III)
Dungeons (at the time of Ultima III)
- Dardin's Pit
- Dungeon of Fire
- Dungeon of Time
- Mines of Morinia
- Mt. Doom
- Perinian Depths
- Snake Dungeon
- In early Alpha testing for Ultima Online, it appears that the original Sosaria continents were to eventually be added to the familiar-but-slightly-different Britannia on release. The image to the right, as well as a image by Raph Koster (care of Cory Doctorow's Flickr account), show the Lands of Lord British replaced by Britannia, but with the other three continents intact. To the right of Britannia is the Lands of the Feudal Lords, below them are the Lands of the Dark Unknown (rotated 30º left), and at the bottom right are the Lands of Danger and Despair (rotated 180º). These lands were never added to Ultima Online, but could give a clue as to how the developers felt the continents best fit together on the globe of Sosaria.
- Garriott, Richard. "The Annals of Akalabeth". Akalabeth Manual (Akalabeth). California Pacific Computer Co.: 1980. Pages 1-2.
- Garriott, Richard et al. "Folklore". The Book of Lore (Ultima V). Origin Systems, Inc.: 1988. Pages 3-4.
- Tavern Keeper. Underworld Dragon's Ultima I Transcript. Ultima I.
- Albert, Dave. "The Adventure". Ultima I: The First Age of Darkness (Ultima I). Origin Systems, Inc.: 1986. Pages 1-2.
- Morris, Andrew. "Lessons of the Past". Beyond the Serpent Pillars (Ultima VII Part Two). Origin Systems, Inc.: 1993. Pages 3-4.
- Garriott, Richard et al. "Folklore". The Book of Lore (Ultima V). Origin Systems, Inc.: 1988. Pages 5.
- Morris, Andrew. "Lessons of the Past". Beyond the Serpent Pillars (Ultima VII Part Two). Origin Systems, Inc.: 1993. Pages 6.
- "Raz's Ultima Page". Artful Gamer. Retrieved 2011-4-11.
|Lands of Lord British (just Sosaria in Ultima III)|
|Cities|| Britain ☥ Dawn ☥ Death Gulch ☥ Devil Guard ☥ Grey ☥ Montor |
Moon ☥ Fawn ☥ Paws ☥ Tune ☥ Yew
|Castles||Castle of Lord British ☥ Castle of the Lost King|
|Landmarks||The Pillars of Protection ☥ The Tower of Knowledge|
|Dungeons (Ultima I)||Death's Awakening ☥ The Dungeon of Doubt ☥ The Dungeon of Montor ☥ The Dungeon of Perinia ☥ The Lost Caverns ☥ The Mines of Mt. Drash ☥ The Mines of Mt. Drash II ☥ Mondain's Gate to Hell ☥ The Unholy Hole|
|Dungeons (Ultima III)||Dardin's Pit ☥ Dungeon of Doom ☥ Dungeon of Fire ☥ Dungeon of the Snake ☥ Dungeon of Time ☥ Mines of Morinia ☥ Perinian Depths|
|Islands and Other Sites||Ambrosia ☥ Isle of Fire ☥ Mt. Drash|
|Lands of Danger and Despair|
|Cities||The Brother ☥ Bulldozer ☥ Dextron ☥ Gorlab ☥ Lost Friends ☥ Magic ☥ Turtle ☥ Wheeler|
|Castles||Castle of the White Dragon ☥ Shamino's Castle|
|Landmarks||Grave of the Lost Soul ☥ The Eastern Sign Post|
|Dungeons||The Dead Cat's Life ☥ The Dead Cat's Life II ☥ Dead Man's Walk ☥ The Dungeon of Doom ☥ Free Death Hole ☥ The Hole to Hades ☥ The Morbid Adventure ☥ The Skull Smasher ☥ The Spine Breaker|
|Lands of the Feudal Lords|
|Cities||Arnold ☥ Gerry ☥ Helen ☥ John ☥ Linda ☥ Owen ☥ The Snake ☥ Wolf|
|Castles||Castle Rondorin ☥ Castle Barataria|
|Landmarks||The Pillars of the Argonauts ☥ The Pillar of Ozymandias|
|Dungeons||Advari's Hole ☥ The Dead Warrior's Fight ☥ The Gorgon's Hole ☥ The Horror of the Harpies ☥ The Horror of the Harpies II ☥ The Labyrinth ☥ The Savage Place ☥ Scorpion Hole ☥ Where Hercules Died|
|Lands of the Dark Unknown|
|Cities||Clear Lagoon ☥ Gauntlet☥ Imagination ☥ Nassau ☥ Ponder ☥ Poor ☥ Stout ☥ Wealth|
|Castles||Black Dragon's Castle ☥ Castle of Olympus|
|Landmarks||The Sign Post ☥ The Southern Sign Post|
|Dungeons||The End ☥ The Guild of Death ☥ The Long Death ☥ The Metal Twister ☥ The Slow Death ☥ The Tramp of Doom ☥ The Troll's Hole ☥ The Viper's Pit ☥ The Viper's Pit II|