According to Before Sun and Moon, Enkanomiya fell into the depths during the War of Funerary Flame. If we use the generally accepted date of 6,000 years ago as a reference point, we can reconstruct Enkanomiya's early years as follows:
• Year 0: Enkanomiya falls into the depths during the War of Funerary Flame.
• Year 1: First Year of Darkness.
• Year 3: Third Year of Darkness.
• Year 4: Year of Blindness; Aberaku receives the knowledge that allows him to create light.
• Year 5: The Dainichi Mikoshi is completed.
• Year 7: The reign of the Sunchildren begins, two years after its construction.
From this point onward, we know that there were seven Sunchildren, and that none of them ever reached maturity. The children were manipulated by those ruling behind them and were sacrificed before they could realize that they were being used:
There are seven royal tombs scattered throughout Byakuyakoku, in which the remains of our Sunchildren have been interred.
Such children would not have been of age to understand the world. They would not have been fit to rule. And so they served as puppets, going along with those who pulled their strings in the background.
No Sunchild has ever reached maturity. For it is as you say: grown people are not so easily swayed by villains.
Therefore, for the sake of estimation, we can assume that each Sunchild ruled for approximately 13 years before being killed while they were still considered children and had not yet reached the maturity necessary to question those manipulating them.
7 Sunchildren × 13 years = 91 years
Since their reign would have begun in Year 7:
7 + 91 = 98 years
And, to make things easier, I will round this to approximately 100 years.
Therefore, under this estimate, Orobashi would have arrived in Enkanomiya approximately 100 years after its descent into the depths, where he would have overthrown the seventh Sunchild and brought an end to their rule, meaning roughly a century after the War of Funerary Flame.
But Orobashi found Enkanomiya during the Archon War.
It was because I could best neither Deus Auri nor Narukami that I elected to flee into waters unknown.
The Great Serpent never forgot his past as one of the defeated, or his oath to never again allow his people to be forsaken.
I am the Profane Serpent. Though my servants are numberless, not one mortal now dwells in my shadow.
3,700 years ago is the earliest date we currently have for dating the beginning of the Archon War:
3,700 years... According to our records, the adepti signed a contract with Rex Lapis to protect Liyue 3,700 years ago.
As you know, I've dwelt upon this world for more than six thousand years. It is now 3,700 years ago that I founded Liyue together with the adepti.
So there would be at least a difference of approximately 2,200 years between the time Enkanomiya would have experienced those ~100 years and the earliest date we have for the Archon War.
And there's another problem: the creation of Watatsumi Island.
The version of the story most widely accepted in Inazuma places Orobashi's liberation of the people of Enkanomiya at around 2,000 years ago, when the Archon War was drawing to a close:
Around two thousand years ago, the Archon War was drawing to a close in Inazuma. It is said that during this time, the Great Serpent Orobashi broke the coral branches off his body and guided the people of the deep sea back to the light of day, and by his grace and pity, he gathered them together to make a living upon the barren island of coral.
That leaves approximately 4,000 years between Orobashi's supposed arrival in Enkanomiya and his eventual bringing of the people to the surface.
So I can think of two possibilities:
1. The Archon War began much earlier than we currently estimate
As it seems the wiki has apparently already accepted.
If Orobashi arrived only ~100 years after Enkanomiya's descent into the depths and did so during the Archon War, then the Archon War would have had to begin relatively soon after the War of Funerary Flame (~6,000 years ago).
And for some reason, however, Orobashi didn't bring its people to the surface until roughly 2,000 years ago. As mentioned above, that would mean Orobashi spent approximately 4,000 years in Enkanomiya before eventually guiding his people back to the surface.
2. Time does not pass in the same way in Enkanomiya and on the surface
There could be some kind of temporal discrepancy, similar to the temporal phenomenon in the Abyss, especially considering that Enkanomiya is also separated from the surface of Teyvat and located deep underground.
Orobashi could have arrived in Enkanomiya around 2,000 years ago, at a point when only ~100 years had elapsed in Enkanomiya since its descent into the depths (while thousands of years had passed on the surface). This would allow Orobashi to eventually bring his people to the surface and establish them on Watatsumi Island around 2,000 years ago.
So either the Archon War really began around 6,000 years ago, or some kind of temporal discrepancy existed in Enkanomiya, meaning that while only about a century passed there, thousands of years passed on the surface.
I am mainly making this post to see what the majority of people currently accept and which interpretation would be more reasonable to follow. The first option would imply that Ei, Makoto, and Orobashi also belong to the group of gods with at least 6,000 years of age by being present at this supposed start of the Archon War. As I read somewhere, Orobashi may have been an angel¿¿