The Guild Wars universe has an extensive backstory, known to players as lore.
Before the Exodus
The oldest records on Tyria date back to approximately 10,000 BE, the estimated date for the Great Giants' extinction at the claws of the Elder Dragons during their last known time of awakening. The only known surviving sentient races of this time are the dwarves, forgotten, jotun, mursaat, and seers. Not much is known about this time, or the following 8,000 years, although it is known that the mursaat had betrayed the other four races and went into hiding from the Elder Dragons. The exact details of this betrayal are unknown, though implications show that this is when the mursaat and seers warred, with the seers being brought near extinction in the aftermath. Only dwarven legends and jotun stelae remain as records of this time. Jotun lore also make mention of an "Age of Giants" that occurred after the Elder Dragons began hibernating, where the various giant races (including jotun and norn) ruled over and guided Tyria - though the credibility of this is uncertain.
Sometime after the fall of the Elder Dragons the charr race united under their new Khan-Ur and conquered the lands around them - said to travel north, then east along the Shiverpeak Mountains, and ending in the lands now known as Ascalon. During this time they warred with the forgotten at the mountainous edge of the then Crystal Sea.
At some point prior to 786 BE the Six Gods arrived on Tyria at the Artesian Waters in Orr from the Mists and later brought humanity to the world. It is said that the Six Gods brought the forgotten to the world as well; however this is now questionable given their dealings with the Elder Dragons. Regardless of their origins the forgotten were tasked as being caretakers as the Six Gods built Arah and terraformed the land.
Although Dwayna and Melandru of the Six Gods encouraged humanity to be peaceful, Balthazar sought to make the world the human's domain, and with his guidance humanity spread. Currently 786 BE marks the oldest records of humanity, being the time they arrived on the northern shores of Cantha and established the Empire of the Dragon in 510 BE. In 205 BE humans arrived in Tyria and Elona, establishing two kingdoms: Orr and the Primeval Dynasty. Over the decades humanity had continued to spread, pushing into Kryta and Ascalon and claiming them for their own.
In 1 BE Abaddon utilized the seer-made Bloodstone to spread powerful magic to all races of Tyria. Although magic had existed prior to this it was in a much weaker state. However, the ability to use magic brought races to war with each other and caused mass destruction and death. To bring an end to the suffering the human king of Tyria, King Doric, traveled to the City of the Gods, Arah, and pleaded with the gods to take back their gift of magic. To do this the gods took the Bloodstone and divided it into five large pieces in Arah, although smaller shards were made from this. Each large stone represented one of the four schools of magic - Aggression, Denial, Destruction, and Preservation - with the last being a keystone required should one ever want to reunite all five stones. To finish sealing magic the gods used King Doric's blood and then threw the five stones into the largest volcano of the Ring of Fire, Abaddon's Mouth.
Abaddon, however, disagreed with limiting magic and rebelled against the other five gods. He transformed the Margonite civilization into ethereal demonic beings and waged war, assaulting the Gates of Heaven. However, Abaddon was defeated and cast down at the Mouth of Torment; the Crystal Sea's floor rose and created the Crystal Desert and the Desolation. The defeated god and his followers were imprisoned in the Realm of Torment, and they destroyed all records of him on Tyria, going so far as to sink his Orrian temple and pull the Temple of the Six into the Realm of Torment with him.
Having caused cataclysmic damage the remaining Five Gods left for the Mists, legends saying they went to create new worlds. This event was called the Exodus of the Gods.
Reign of Humans
Historical records after the Exodus primarily focus upon humanity. Ever since 100 BE the known world of Tyria, Elona, and Cantha was under the domain of the human nations: Ascalon, Orr, Kryta, Elona, and the Empire of the Dragon. Two years after the Exodus, Orr became an independent nation. Humanity continued to spread, eventually forcing the Forgotten into the Crystal Desert in 174 AE where they became caretakers to Glint and guardians of the trials of Ascension.
Over the following century, after the Exodus, human culture established guilds which became powerful groups in the nations. They began to hold more power, being the enforcers of laws and regulations in whatever means they desired. In time their influence began to overlap bringing conflicts. But that was not until the volcano in the Ring of Fire erupted sending the five Bloodstones across the land; the magic they contained seeped into the land and air around them. With greed and the desire of power in mind, the guilds attempted to claim these Bloodstones.
Because so much power was in the hands of guilds, the kings of Ascalon, Kryta, and Orr were unable to prevent conflict and the first Guild War began, raging for decades. In time, Ascalon and Kryta were embroiled into the war; only Orr remained outside the Guild War, preferring to remain neutral and peaceful. In whole, there were three Guild Wars. When the first two began and ended are unknown.
221 AE marks the beginning of what Canthans call the Age of the Hedgehog; it was when Canthans made official contact and trade with the northern continents of Tyria and Elona. In 300 AE, Kryta became an official colony of Elona, although humans had lived on Kryta since the time of King Doric. This time marked the beginning of the human-centaur conflict as humans had spread further out and into centaur lands. Kryta gained its independence 58 years later.
452 AE Saw the first fall of a human nation. The Scarab Plague began, sweeping through Istan and wiping out the Primeval Kings. After the Scarab Plague subsided the Great Dynasty was established until its fall after 127 years. The Great Dynasty was followed by Elona's darkest times, the Shattered Dynasty Era. Although wars raged on, and leaderships changed, the human nations saw little historical effect until 851 AE. Lord Odran, through sacrifices and powerful rituals, became the first mortal to open portals into the Mists. Although the portals lay hidden in dangerous lands his eventual death brought new sport to both man and spirit: tournaments of glory held within the Hall of Heroes.
Two decades after Odran first opened portals to the Mists, Abaddon began his plot to return and bring forth Nightfall. In 870 AE the Flame Legion of the charr discovered the titans, agents of Abaddon, at Hrangmer, worshiping them as gods of their own. Bathea Havocbringer rebelled against this new worship, raising an underground army to disrupt the Shaman caste and their new faith. But she was defeated, and sacrificed to the new gods. In turn, the Flame Legion banned all females from fighting in battle, forcing them to domesticated tasks at homes and on farms.
Two years later Shiro Tagachi slew his own emperor under the influence of the words of a Fortune Teller, who also was an agent of Abaddon. Through dark rituals Shiro absorbed magic granted to Emperor Angsiyan from Dwayna and twisted it. Upon being slain by Viktor, Archemorus, and Vizu Shiro released this magic in a death wail, causing the Jade Wind.
Abaddon's plots were not heard of again until the end of the Third Guild War, which began in 1013 AE. When the nation of Orr was eventually forced into battle, though they intended to end the conflict under King Reza's orders, the casualties rose exponentially compared to the past two. This third war did not end due to Orr's influence, however, but by a blitzkrieg attack from the charr. In 1070 AE, the charr assaulted Ascalon while they were distracted with Kryta and Orr, and quickly made it to the Northern Wall, where they performed the Ritual of the Searing. Ascalon was devastated, and the charr armies marched through with ease, bringing more Searing Cauldrons with them towards Orr and to Kryta.
With the Orrian armies away, the charr swept through Orr with ease despite their magical affinity. They quickly made it through to the western edge of Orr, now known as the Cursed Shore, though never had the chance to reach the actual city of Arah. This was due to Vizier Khilbron, a possible follower of Abaddon, unleashing a powerful spell that sank the peninsula of Orr in the Cataclysm - although there is conflicting information upon whether the destruction of the nation was intentional or done out of desperation. Either way, the only survivors of this event were those who were away from their home at the time; all those who were in Orr during the Cataclysm became the walking dead, Khilbron himself becoming a Lich Lord.
Kryta shared a different fate. When the charr forces arrived King Jadon fled the throne, leaving his people at the mercy of the feline race. However, a newly formed order stepped up to defend their land - the White Mantle, led by Saul D'Alessio. The White Mantle, backed by the mursaat whom they called the Unseen Ones, successfully defeated the charr, although at the price of the lives of the unfaithful who witnessed the Unseen Ones' true form - including Saul himself. With the royal family gone and Kryta leaderless, the White Mantle rose to power as the new government, savior of the lands.
With Orr sunk beneath the waves and Ascalon in ruins still fighting the charr High Legions only Kryta remained among the human nations of continental Tyria. In 1072 AE Ascalon was further weakened. With the charr pushing ever further Prince Rurik began to believe that they should retreat to another land and regain their strength to take back Ascalon in the future. His father, King Adelbern, was outraged at this. After the fall of Rin, the second capital of Ascalon, Prince Rurik was exiled from the land. Rurik did not leave alone, however. He offered the people a chance of a new life in Kryta, and began the Ascalonian migration west.
Crossing the Shiverpeak Mountains the Ascalonians met resistance in the form of the Stone Summit dwarves, a splinter faction of Deldrimor. In crossing the Shiverpeaks to protect his people Prince Rurik sacrificed his life to hold back the Stone Summit. At this time Kryta itself was attacked by undead under Khilbron's command, in the hope of finding the Scepter of Orr and fulfilling the Flameseeker Prophecies - which foretold the extinction of the mursaat and the White Mantle's fall and the release of the titans from behind the Door of Komalie. Although originally saviors, the White Mantle fell to corruption and - under the orders of their Unseen Ones - they sacrificed innocents to power soul batteries to prevent the Flameseeker Prophecies from coming to pass. This in turn sparked a rebellion within the land: a war between White Mantle and Shining Blade. Through the help of Ascalonian heroes and the Shining Blade the Flameseeker Prophecies were completed: the mursaat who hadn't been killed had fled, the White Mantle's leadership destroyed and the heir of King Jadon, Salma, found. The titans themselves were locked away once more after Khilbron's death.
Tyria was not the only continent besieged with problems however. Across the Unending Ocean, in Cantha, Shiro Tagachi returned as an Envoy and brought forth the Affliction, decimating the Empire of the Dragon and their population. However, Shiro was eventually defeated, and the Afflicted were wiped out over the next eight years by the newly formed Ministry of Purity. Cantha saw a peaceful time once more, although still affected by the events that occurred. Of all human nations, Cantha remained the strongest.
In 1075 AE, Elona saw the fruits of Abaddon's plot in the form of Nightfall. Demons from the Mists entered the land, and through Abaddon's power the land itself was slowly transformed into a nightmarish version of its true self. Through the united efforts of the Order of the Sunspears and the Order of Whispers, Abaddon was eventually defeated. But a god's power cannot be destroyed. To prevent Abaddon's rampant energies from annihilating Tyria Kormir rushed into the colliding energies uncertain of what would happen, and she came out as the new goddess of truth.