This is a Fictional-theory by me,

Lets, go through a short Recap of the story of Jin Wei and Wei Jin again...

Team Avatar, comes to the Great Divide, and finds a conflict between two tribes, Zang and Gang ji. Their earth bending guide lost his arm during their journey, Team avatar helps both tribes by helping them to cross the great divide.

They come across the story of Jin Wei and Wei Jin..

Jin Wei given an important job, carrying a Crystall orb from the Eastern Gate post of their tribe to the Western Gate to symbolize the sun rising in the east and setting in the west. The goal of the journey had been to purify the tribe's connection to the spirits. this is called redemption ritual.

Sacred crystal orb

Now let me come to the theory...Why should some one, carry a crystal orb from eastern gate to western gate? Clearly there is some logical explanation behind this ritual.As you can see,Jin Wei carrying the crystal orb is to track path of sun rays, coming through both gates.This is clearly a measurement device.Are they tracking the path of heavenly bodies? is that about calculating the next alignment of planets? 

The story happened to a 100 year ago.

As you can see there is no religion on avatar universe, only the avatars have their temples, everyone are worshiping the past avatars, According to tenzin, Even the most spiritual place on the air-temple is the statue room of past avatars.Even more elders of all nation (like fire sages,white lotus), is serving the avatars.So all rituals on avatar universe, must some thing related to the avatar.I guess, some avatar (warned by past avatars or raava) wants to know the exact date of next planetary alignment.That's why i think, the culturally advanced, tribe of Zang given the job of measuring the movement of planets and sun.

The alignment of planets is called Harmonic convergence,

Planetary alignment

Let's analyse the ritual even more...

the meaning of "redemption" is "the action of saving or being saved from sin, error, or evil"

In other words, "The action of saving someting(possibly the world) from evil".So the name of the ritual is clearly shows that it is an action of saving the world from evil, in other words Vaatu.

Great Divide
Even more, This is the great divide, The guide said, this canyon carved by angry earth spirits. who are angry at local farmers.Spirits angry at local farmers.? This clearly a made-up story!I am thinking that this is the same place... were raava and vaatu fought during last harmonic convergence

These are not the only reference.. 

Words of fortuneteller clearly a reference to Korra-Vaatu battle...

Book 3 clearly showed firenation is NOT evil, just a bunch of decent guys under a tyrant ruler.So, the battle between forces of Good and Evil is not about firenation, but about battle betwen Korra and Unalaq. Lion turtle Only Game "Energy Bending" to Aang NOT for defeating Oozai, He gave Energy bending so that korra can defeat Vaatu,

So, These are the References of previous or next Harmonic convergence in Avatar:Last airbender..

  • The Great Divide Canyon
  • The Sacred Orb and redemption ritual
  • Zuko alone atmosphere is the same place were wan died
  • Fortune teller's prophecy
  • Lion turtle's advice to Aang

Your thoughts on my theory...

Community content is available under CC-BY-SA unless otherwise noted.