Sage Agasthya is mentioned in the Rig Veda : in fact he authored hymns 166-190.
He is also mentioned in Tamil Literature, Sangam as well as later works in Tamil.
He is credited with the firs grammar book in Tamil,Agathiyam, which was followed by Tholkappiyar later by about 300 years(there is some discussion on this).
The Agastya mentioned in Tamil has been dated somewhere around 3000-5000 BC.
On the other hand, the Agasthya mentioned in the Vedas, Puranas ,Ramayana and Mahabharata is dated earlier.
Agasthya was the one who taught the Adhitya Hrudaya stotra to Lord Rama in the battle field .
Mahabharata recounts the story of Agasthya, Ilvala and Vatapi:Vatapi was swallowed by Agasthya.
Tamil literature says that he was entrusted with the task of spreading Tamil by Lord Shiva who is believed to have founded Tamil and Shiva was the Chief of the First Tamil Conclave at Then Madurai, which was swallowed by a Tsunami.
This event concurs more with the Times of Ramayana than with the Mahabharata.
Even then this can not account for Agasthya being mentioned in the Rig Veda.
Though earlier studies have indicated that the Rig Veda was composed around 5000 BC, latest researches say that it was composed much earlier, some 25000 years earlier.Please read y post on this.
There are indications that the Rig Veda might have been composed in the Arctic.
I have an article on this.
So we have a confusion.
What is the date of Agasthya?
5000 BC or 25000 BC?
There is also a view that there were more than one Agastya.
Comparison of works in Tamil by Agastya nail this lie perpetrated by the West to misinform the world about the antiquity of Sanatana Dharma and Tamil.
There was only one Agastya. who composed the Rig Vedic Hymns and Tamil Classic Agathiyam.
How does one reconcile this anomaly in dates?
Legend of Agasthya states that as he was traveling from the North towards the South, he had to cross the Vindhya Mountains, which was growing quite tall to compete with the Himalayas and it was feared that it would affect the Skyline(Heavens).
The Devas represented this to Agasthya who was the Guru, Teacher of Vindhyas.
So when Agasthya crossed the Vindhyas,it prostrated before Agasthya as a mark of respect and Agastya told the mountain to remain in that position to enable him to cross and recross.
Agasthya crossed over to the south and did not return to the North by Land.
And the Vindhyas remained prostrated.
( Sage Agasthya traveled to the North from the South by the Sea) .
There is a Star called Agasthya in Hinduism and it is referred as having been sighted by Agastya; in fact it is named as Agasthya.
It is the Star Canopus.
One Canopus sighting per 25, 000 years .
Each Yuga should have had as many Sightings of Canopus as there are/were 250000 Years.
Conjoin this with Cyclic Theory of Time according to Hinduism which is now being accepted as a reasonable estimate of Time scale.
Please read y post on the Cyclic theory of Time, under Astrophysics.
We arrive at the conclusions.
1.Agasthya existed in Ramayana, Purana ,Mahabharata and Times.
He also existed at the time quoted by Tamil Classics.
2.This validates that Tamil and Sanatana Dharma were interlinked.
3.That Time is Cyclic and the events occur in Cycles.
4.Tamil Language is as old as Sanskrit.
5..Agasthya existed around 5000 BC and around 25725 years before that.
Citation. Check for Images , calculations.