Throughout the recorded history of mankind, kings and queens; emperors and empresses, must recite an oath before their followers and subjects as they ascend to the throne.
Men shall not covet the realm where Sacred Beasts roam
lest they seek to shatter the ensuing era of peace and harmony
Under the witnesses of the Forest Elders (Caretakers),
this oath shall last as Time permits.
And this oath is remembered throughout the land and across the ocean as The Ancient Oath.
No one remembered how ancient ago the oath was made.
Even if the origin and history behind it are twisted and forgotten, as long as every word of the Ancient Oath continues to be passed down to every generation until the oath becomes a fairytale of the past.
What's truly important is that as long as there are Sacred Beasts roaming, flying, crawling and swimming somewhere, the content of the oath must be respected.