This is an attempt to create a rough chronology of the canon background story (as described in official NEXON/KRU recognized events, not PC history. Official canon supersedes any player-created histories if the events conflict, so this is important to pay attention to)
For this point of game lore history, I will use the date B.Y. (Before Yuri).
~Pre-Yuri History~
(the point of history prior to the events which take place during the game time line)
B.Y. ?? – ChiZao is born a mortal scholar in an unknown and ancient tribe of humans that lived in the area of what is now Buya and Koguryo.
B.Y. ?? – ChiZao stumbles upon a hole in the barrier between our world and the ethereal one, becoming the living embodiment of magic in the process. He learns much from the ethereal spirits (most likely the ones from the Ethereal Temple event, but perhaps also Bon-Hwa?). ChiZao returns to our world and passes on his knowledge to four students who become the Guardians of the Four Directions: Chung Ryong, Baekho, Ju Jak and Hyun Moo. Together they teach all the people of the world about magic.
B.Y. ?? – ChiZao falls into insanity, becoming corrupted by his power. He becomes an undead being of evil. ChiZao raises the dead as an army of zombies and taints creatures of the world, twisting them into darkness (The Haunted Houses originate to this period of time, as do the Crypts south of Koguryo . I speculate that Man-Shik may also have been created at this time).
The Four Guardians lead humans tribes in a battle against ChiZao’s forces, ultimately defeating and sealing him away inside a tomb as to prevent the loss of magic in the world, for magic begins and ends with ChiZao. This tomb is located in what is now Nagnang.
B.Y. ?? – Over the years, ChiZao’s powerful magic leaks out from his tomb, infecting the creatures intended to guard him. This area becomes known as the Vortex. The simple mechanical lock on ChiZao’s tomb proves ineffective, so the Mythic Animals are created by the Four Guardians and charged with guarding the Elemental Keys that seal ChiZao in his tomb prison. (previous canon that King Yuri was responsible for the Mythic Animals trapped inside their caves was ret-conned by this storyline)
B.Y. ?? –The Zibong are born, possibly as a collection of spirits that formed together to become a collective-consciousness of entities capable of feeding on the souls of other creatures, absorbing their power. (possibly originating from souls of those who died fighting ChiZao?)
B.Y. ?? –The Zibong conquer an unknown but pacifistic race of beings steeped in magical power.
B.Y. ??- The Zibongs either withdraw deep into the earth under Du Mountain or become entrapped there by some other force.
B.Y. ?? –A race of trolls create what becomes the Lost Mines. (trolls possibly related to the ogres?). They release the Zibong and are annihilated, but not before sealing the mine. Zibong escape nonetheless.
B.Y. ?? – The Wind Temple is constructed / brought into this world (origins are unclear; I assume must take place after ChiZao introduces magic to the world). The Wind Gods Hanuman, Hwanung and Tangun may also have been born at this time.
B.Y. ?? – Zhixin forges a Staff of the Elements (this event must take place prior to the birth of the Han Empire)
B.Y. ?? – An unknown warrior tribe captures the Wind Temple, sealing the Wind Gods spirits inside of shrines located within, allowing them to use their power to control the Wind spirits. The tribe uses the Wind Temple to defeat many other tribes. This results in the birth of the Han Empire.
B.Y. ?? – The early Han Empire sends the Wind Temple high into the sky to prevent others from using its power.
B.Y. ?? – The Spirit Guide Eldridge is born and granted power by the Gods to guide mortals (this event must take place about here as Eldridge knows little more than legends about events prior to this point)
B.Y. ?? –The fishing village of Hausson is founded off the coast of what is now Koguryo. Hyun moo becomes the guardian deity of the village.
B.Y. ?? –Pirates attack Hausson. Hyun Moo calls for the aid of the other guardians to repel the attack. They are successful, but at the loss of Hausson’s strongest warrior, Kimesh. The totems bless her with immortality in spirit form and teach her how to create weapons infused with their own power.
B.Y. ?? – Min, Chul and Jae-Hwa discover the Wind Temple. (( as Min is closely associated with the village of Hausson, I think this may be the appropriate time period ))
B.Y. ?? – Mupa is born
B.Y. 12 – Yuri is born
B.Y. ?? – Sagu is born
Yuri 1- Yuri becomes King of Koguryo
Yuri ?? – Prince Mhul is born
Yuri ?? – Princess Yun is born
Yuri ?? – Mhul befriends the Sea Nymph.
Yuri 16 – Game events begin
Yuri 16-17 – Mupa comes to Koguryo and entrances Sagu. Mupa attempts to kill Princess Yun but is chased away by Mhul. King Yuri banishes Mupa from Koguryo. Sagu leaves the kingdoms to follow Mupa, swearing revenge.
~Events I’m not sure where to put~
B.Y. ?? -Ho-lu’s battle with a mage and his undead army of skeletons; creation of the Spirit sword
B.Y. ?? -Prophecy of the Spirit Arrow is divined
B.Y. ?? -Sea Nymph’s birth
B.Y. ?? -Birth of ogres and Hamgyong Nam-Do founding