Tyria, the planet, not to be confused with the continent of the same name, has been the home of many sentient species such as the humans, charr, asura, sylvari, norn and hundreds of others. Known history puts it over 11,000 years old, when Giganticus Lupicus and Elder Dragons last roamed the world. While it was originally believed by humans that Tyria was created by the Six Human Gods, and the first among them, it is now known that the gods traveled to the world from somewhere else, and the earliest known human life is recorded at 786 BE. It is not known how many planets predate Tyria, or how many other planets there are in the multiverse known as the Mists.
There are currently three known named continents on Tyria: Tyria (which shares the name of the world), Cantha, and Elona. Between Cantha and the two northern continents lies the Unending Ocean, and north of Tyria is the arctic ocean where the kodan's sanctuaries once resided.
Based on a globe found in the Chantry of Secrets, the world of Tyria consists of four continents, one being a supercontinent containing Tyria and Elona, and several large island chains. This globe reflects the passage of time, with alterations to show the damming of the Elon River, and apparent changes to the northern coast of Cantha. It does, however, have a few inconsistencies with other contemporary maps, for example not showing the sea formed by the rise of Jormag in the Far Shiverpeaks, or the arctic sea that was the former home of the kodan. The delta north of Kryta leading into what was once Giant's Basin also appears to be missing, and the land extends too far north so that Janthir Bay is completely missed off the map.
The true age of the world is unknown, with the oldest records dating to the approximate extinction of the Giganticus Lupicus in 10,000 BE. This was the time of the Elder Dragons' last time awake, having brought the Giganticus Lupicus into extinction. Few records exist of that time, as only five sentient races are known to have survived that time - the dwarves, forgotten, jotun, mursaat, and seers. Of those five, only the dwarves and jotun kept records of the time, but since then all five races' culture has fallen into ruins and only the jotun remain, though as savage primitive forms of their ancestors.
At some still-unknown point in the past, powerful beings known as the Six Human Gods traveled to Tyria, bringing humanity with them and ushering a new age. Under the guidance of Balthazar, humans spread and conquered lands across the world. The oldest known nation of humanity being Cantha - first settled in 786 BE. In 205 BE, humanity traveled to the northern continents of Tyria and Elona, and established the kingdom of Orr and the Primeval Dynasty in their respective continents. Encouraged by Balthazar, humanity continued to spread across the world, waging wars with the native inhabitants and pushing them from their lands. In time, they establish Ascalon in the land previously conquered by the charr and made settlements in Kryta.
In 1 BE, Abaddon used the Bloodstone to grant magic to all the races of the world. However, this gift backlashed as wars between the races and people grew and intensified. King Doric of the Tyrian human kingdoms pleaded to the gods to take back their gift, and to do so the gods divided the Bloodstone into five pieces - each representing a different school of magic (Aggression, Denial, Destruction, and Preservation) as well as a keystone required to reunite the Bloodstones into one again. They then used Doric's blood to seal the magic and dropped the bloodstones into Abaddon's Mouth, the largest volcano in the Ring of Fire islands. Magic remained in the world, but greatly reduced in its power and efficiency.
However, Abaddon, had disagreed with removing magic and rebelled against the other gods. As they brought him down, the five gods created the Crystal Desert and the Desolation, and sealed Abaddon in his own realm, the Realm of Torment. Because of the devastation they caused, the gods left the world in the Exodus of the Gods.