Tara

The Known World
Tara has four major landmasses; Ur, Yavanna, Ys, and Vaalbara. Near Vaalbara lies the Rift, a maelstrom of energy that bends space and time around it while disgorging magic into the world. None of these continents (save Ys) have ever been completely mapped. Although the world is widely reckoned to indeed be round no explorer has ever managed a successful circumnavigation of the globe. This is because beyond the Vanishing Isles lies the "Expanse", a vast and featureless ocean. Other notable seas include the Pale Sea, the Tiberian Gulf, the Sea of Souls, the Waking Sea, and the Savage Sea.

State of the World
The Age of Men is over.

It has been 200 years since the "Endings", which saw the collapse of the Tiberian Ecumene and most of Ur lain to waste by dragons. The nights were lit by burning cities; ash winters smothered the land. Those few, desperate survivors left fought over what little remained, praying that they might someday find green, safe lands. Only at the edge of the world - far from the heart of what was civilization - can such places still be found.

The Shield Marches, once Tiberium's frontier, were practically untouched by the Endings, having been too far away to attract much attention. For the last 200 years the Marches struggled to secure their borders, hardly producing enough to feed their own people let alone so many refugees. As these attacks grow less frequent the Marches have become distracted by infighting, their ancient rivalries having only been temporarily set aside against a common threat.

New, fledgling nations have also emerged; Canton, Denedell, and Freesia - the result of a hunting argument between three brothers - were settled by refugees. Two centuries ago Seawall, a fishing village, became a safe harbor for all the ships stranded at sea and today is a sprawling city-state.

Sailors even bring tales of lands beyond the cities of the dead, past the stone teeth of the mountains and the great sands. The great city Amaranth that guards the Gates of the Sea. Yavanna and its thousand Princes. Hue, the hermit kingdom. But for most these far away places may as well be children's stories.

Ur
Ur is a fractured supercontinent, the youngest and largest of the world's major landmasses. Straddling the equator it is divided in half by a mountain range called the Dragonback Spine. The drier half of Ur - Outremer - is an immense desert in the mountain's rain shadow. The windward face, however, is far more hospitable. The continent is connected to Yavanna by a narrow, curving isthmus and separated by the Gates of Sea, a manmade canal. For two thousand years the continent was unified under the Tiberian Ecumene. Ever since its collapse during the Endings the land has been depopulated, although it has recovered dramatically in the last 200 years.

Yavanna
Below the equator, south and east of Ur, is Yavanna. A much richer, more densely populated continent, it shares the Tiberian Gulf (a practically landlocked sea) and a narrow isthmus with its neighbor. Yavanna's climate varies from tropical to glacial and super-arid thanks to its immense mountain ranges, which render a chiaroscuro of steaming jungles, deserts, snowy peaks, and mighty glaciers. For the last 8000 years it has been enthralled by the Summer Court, an elvish polity. Elves and men have mingled together over the years, becoming one race divided by a strict hierarchy called the "blood-castes".

Yavanna also encompasses the nations of Hue and Porte

Ys
A large, forbidding islands located between Yavanna and Vaalbara in the Savage Sea, Ys is dominated by a single massive shield volcano called Krakouro (itself part of a great chain of more than fifty volcanic islands called the "Balefires"). Vicious storms batter its coasts; spikes of black rock - "dragonsteeth" - rear up out of the surf; and tenacious jungles grow back with astonishing speed. The wildlife is just as strange and terrifying - many species, including wyverns, marrow leech, and siltwalkers - are found nowhere else in the world but here. The men who dwell here - "Mer" - are cannibal seafarers who've picked their neighboring islands clean of human life and are notorious for raiding far from their home in search of fresh meat.

Vaalbara
Today regarded as a lost continent, Tara's southern pole was also its oldest landmass (though nowhere near as large as Yavanna or Ur). Lying in the Sea of Souls very little is properly known about it other than it was once the first home of the elves, who abandoned it after a long and terrible war.There are many conflicting accounts of this place. Some stories tell of fogs that cover the land like a shroud, hiding things better left to the imagination than the light of day. Others claim the seas boil away into steam; dead forests crumble into dust in the breathlike wind; mountains float; ruins built to an inhuman scale; starless skies; and an unnerving, impenetrable stillness. Few ever return from Vaalbara; the mad adventurer Bazzaro Realis founded a lost colony there. What survives of his diaries claims that the island drove him sane.

Old Dawn
The Pan (fauns) are reckoned to be the first of the world's creatures and eldest among its children. In their time they have forgotten more than the younger races have ever learned. They possess a deep, intimate knowledge of the natural world. Most have been alive since the Old Dawn and remember how the land warred with the sea. They dwelled in harmony with all living things.

Gathering Storm
When men were still only primitive islanders the Chiron were a sophisticated race of warrior-scholars, prophets, and stargazers. What they saw in the stars troubled them; they foretold a storm that would never end, swallowing the stars and bringing doom upon the world. Most chose to leave Vaalbara and the thunder of their hooves raised a land-bridge that parted the Sea of Souls. A handful remained behind as a vengeful rearguard while their kin fled. Yet they were not alone - the Pan chose to gather in Vaalbara. There they prepared to greet the storm.

Eye of the Storm
The fauns made preparations, hoping to restrain the storm. With the help of giants they raised fields of enormous monoliths carved with runes of power. When the storm came there was no great spectacle; the world dimmed, and there it was - the Rift. As it unfurled over the land the stars went out, yet when it reached the wards the fauns had prepared it turned into a swirling maelstrom of violent energy. After a long while the storm calmed, its rage spent.

The Pan had hardly recovered from their labors when a new threat emerged from out of the eye of the storm. No sooner had these beings emerged from the Rift than the chiron fell upon them. Yet for all their wrath and skill even these warriors were no match, slaying only a few before being torn apart by raw power. Sensing the Pan trying to restrain them they fought back - after a brief battle of wills the fauns yielded.

New Order
Many of the fauns had perished and without them the wards that held the storm began to fail. Those left alive submitted themselves to the "Siorai". These begins were incorporeal wraiths born wholly of the Rift's energies. It took all their strength to maintain their hold on reality. When they learned they could never return to their home plane they desperately sought the fauns' counsel, feeling stranded and vulnerable on an alien shore. The fauns led their masters to the Root of the World in Ur. There they were reborn as elves, physical beings now bound to the world and its fate. Shortly thereafter the fauns crowned Nuada Argetlam as the first (and only) king of the elves, convincing him to break with eons of unspoken tradition.

Rise of the Elves
Argetlam would found an elvish dynasty that would last another 6000 years and rule over two continents. But his choice divided his people forever. The Kindred chose to stand apart, remaining in Land's End to care for the Root and the Oldgrowth forest. The "young court" gathered around Mab, the first elvish child born on Tara, and left for Yavanna; cradle of human civilization. There they learned how to enthrall men to their will and ultimately came to rule the entire continent. Those men who resisted were exiled into what is now Amaranth. Meanwhile the Winter Court began to take shape - a secret society aware of the fauns' deception and committed to protecting their people from all threats...even themselves.

Age of Men
The Amaranthines would found a great empire and ruled the rivers and seas for millennia. But eventually a challenger emerged; the Tiberian Ecumene. The Tiberians had enjoyed Amaranthine patronage and conquered most of Ur, forging a continental empire that eclipsed their old patron. Yet their ambitions proved too great. A fruitless invasion of Yavanna brought a disastrous war with the elves, from which neither side ever truly recovered.

Last Endings & the Fallow Wars
The Tiberians spent the next 1000 years sinking into decline, the Ecumene eventually collapsing under its own weight. The elves, humiliated by their defeat, were plagued by infighting and civil war that left Vaalbara uninhabitable. What followed was 200 years of chaos; the Fallow Wars. Today the world is a very different place; much of Ur and Vaalbara have been depopulated or left uninhabitable. Men and elves fight a vicious struggle just to survive, let alone regain their place in the world. Their Age is over. What comes next is anyone's guess.

Siorai (elves)

 * Kindred
 * Winter Court
 * The Blood Castes
 * Caravanserai

Major Faiths

 * The Myriad 
 * the name of the Tiberium's great patheon, the Myriad contained over 10,000 gods from every culture in the Ecumene. 2000 years of trade, conquest, and assimilation saw the Ecumene absorb countless peoples into their empire, and they brought their gods with them. Although a strictly secular state the Ecumene tolerated them so long as the faithful still provided that tribute most important to the empire; blood and treasure. Some notable cults included;
 * The Brazen Bull
 * Sea Shepherd
 * The Flame Undying
 * The Sword Bearer
 * Raven
 * Witch-Queen (Mab)
 * Weeping Child
 * The Far Wanderer
 * The Burned Man
 * The Kindly Lord
 * MirrorMirror
 * The Pale Mare
 * One God
 * Physic (healing)
 * Night Weaver
 * The Red Huntsman
 * Moon goddess
 * Horned Gods of the Wood
 * The Ghost Ship
 * Loom (god of prophecy)
 * Baathyal the Void Queen
 * X - A remarkably popular fertility cult that worshiped a hermaphroditic god of unknown origin, the X gained a tremendous following in the Ecumene. At its peak it was even sponsored by the state, which set aside one festival a year for a night of public orgies. All procreation was considered sacred (though the cult was violently homophobic). This ended when a plague - syphilis - decimated the empire. The cult fell out of favor, its priests grotesquely twisted by sickness they had unwittingly spread, and spent their last years tending the sick.
 * Deathshead Cult - It is not known when the death cult first emerged. Some scholars have found evidence of it in Amaranth, Iskander, and even in the Vanishing Isles. The Blind Fates - oracles and vestal-brides of death - have appeared time and again throughout history, always appearing in the last days of great civilizations. They possess unnatural powers, able to divine the most terrible futures (wars, murders, stillbirths, etc.) and could sense mortality through touch alone. They were shunned by the Tiberians who confined them to the Temple of the Fates in the old ruins of Pallas-Ides. Just before the Ecumene's collapse the cult's popularity reached a fever pitch as the people felt their prayers fell on deaf ears and turned to the one god who still answered them. Death. To this day it is rumored that the Fates still linger in what was once Tiberium and tales of similar figures appear in other cultures. In Yavanna they are called "Untouchables".
 * .The Word - the Word is the dominant faith in Ur. Its worship revolves around knowledge left to mankind in a mysterious Book, a huge tome written in the Dead Speech of Tiberium. It was found in the ruins of Numitor, miraculously untouched by the dragonfire that had claimed the rest of the city. Because it could not be moved the Readers established their headquarters there. They came to care more about preserving knowledge than tending the faithful, adding their accumulated wisdom to the Book (which, astonishingly, remains blank). They built a fortress-monastery around the Book to protect it, believing that one day this knowledge would save mankind. They live as monks, eventually going blind from copying texts. Readers are found in all corners of the world, seeking out the relics and scrolls of a lost age.
 * The Readers are postreligous/agnostic, believing that God is an unknowable being. Some claim its will is expressed through the laws of nature - math, science, etc. and that only through knowledge can men become closer to God.
 * Most of the faithful are simply content to put their trust in the authorities, believing they know best. After all the Readers have brought vast improvements to their lives (improvements to agriculture, medicine, engineering, etc.), thought they enjoy only a fraction of the comforts once found in the Ecumene. Laypeople are kept in the dark by the nobility, many of whom ban literacy to prevent peasants from empowering themselves. Many Readers also share these notions, knowing their knowledge is power.
 * Only the most venerable Readers are allowed to read from the Book; some claim they see its words when they close their eyes and that when they read it their inner voice sounds different. The meaning of its texts shifts somewhat depending on the reader; over time this has led to schisms in the faith.
 * The Readers' militant branch, the Swords, experienced a factional schism. Many believed that guardianship extended to protecting the innocent, a view not shared by those Readers who valued knowledge over human lives. There is still bad blood between the two orders because those who left took relics and texts with them and go out of their way to educate the common man, weakening the Readers' control.

Magic
In my setting magic is more like natural phenomena (think weather or radiation). It's a very powerful force but it's also dangerous and uncontrollable - you can't channel it and it's something you'd want to go out of your way to avoid.

Magic leaks from another dimension through a rift in time/space. Close to its event horizon the rift actually warps the laws of nature and over time the magic energy its disgorged has mutated living and nonliving things.

There are minerals like Lodestone and Quicksilver that have unnatural properties thanks to their higher concentration of magic (floating mountains, etc.). The same goes for some plants and animals and there are even humans born with weird mutations (multiple limbs/heads, animal patterned skin, albinism, twins, elongated skulls, etc.).

Alchemy is the closest you can get to a handle on magic because it basically boils down to studying things that have been affected by magic. Prophecy is the result of the rift affecting time itself. Blood magic is possible because practitioners have high levels of magic in their bodies, and for the most part its bullshit. The oldest living elves can work "glamors" - illusory magic - because they were not born on Tara and were once incorporeal wraiths who had to maintain physical bodies.

There's no real "rule system" to magic; it just does what it does.