Let us try to find the probable date. This is based on the premise that if X mentions Y , then X is later than Y.
Purananooru - 378
Purananooru mentions mentions Rama and sita ,so it cannot be more than 4000BC old.
Purananooru mentions mentions Mahabratha war so, it is atleast later than 3000BC
Purananooru - 175
Purananooru mentions mentions Maurya ,so it is later than 175BC atleast.
purananooru mentions Ilamcetcenni stopped Mauryas from coming to south, Silapathikaram mentions Karikal chola who is dated (by most ardent tamil chuvanists) to be in 2nd century AD. So Father-son ruling 500 years apart. which shows that the the poet who composed the poet cannot be dated anywhere near the two dates. so give atleast 200 years to forget the periods , that puts purananooru to 400 AD.
Killivalavan was a chola king mentioned in Sangam Literature, and Father of Nedunkilli and Nalankilli , in the Purananuru and Agananuru.The etymology of Killi is kilai (Branch in Tamil)
The word Pallava means branch in Sanskrit, denoting that they are a later offshoot (Kilai-> Branch(tamil)) of Chutus (satkarnis).Pallava is rendered as Tondaiyar in the Tamil language. The Pallava kings at several places are called Thondamans or Thondaiyarkon. The territory of the Pallavas was known as Tundaka Visaya or Tundaka Rashtra.(tundaka -> Branch) The Sanskrit meaning of Pallava is Kilai The Tamil Thondai means the same, It shows that Pallavas are descendants (Kilay or Pirivu) of Chutus(satakarnis). Karnata dynasties Chalukyas and Rastrakutas call themselves Vallabhas and Pallava also from Karnata have called themselves vallabhas in some places, which translates to valavan in Tamil.
If we take the killi ->; Kilai and Pallava ->; kilai and vallabha -> valavan
We have killi valvan and it shows that killi valavan is generic term applied to pallava vallabha.
After the pallavas revenge against pulikesin II, Ganga king who had marital relations with chalukyas took revenge against pallavas and chased them out of kanchi. So the pallavas shifted themselves to a place called Kaduvetti, which is now in chola country. Many of their inscriptions are from kaduvetti. Only after this time we see cholas rising. Cholas might have marital relations with pallavas and putting killivalavan as one of their ancestors, shows their ancestors are pllavas. Until Nirputunga pallava cornation ,they were feudatories of pallavas. This also solves myth Pallavas are not mentioned in Sangam literature-so sangam literature has to be dated before pallavas. So if we take this account then the purananooru has to be dated after pallavas that after 9th century AD.
Karikala, Maurya ,Ramayana and Mahabharata war
There is a karikala known as Aditya Karikala ruling in 9th century AD. Mauryan kings were ruling until 7th century AD in Konkan. So the knowledge of Mauryas and Karikalan were fresh. During 9th century AD to 13th century AD, saw all the dynasties trying to connect themselves to Ramayana and Mahabharata Warriors, not surprising the Purananooru does similar act of connecting the tamil kings to Mahabharata heroes. Karikala said to have defeated Oliya nagas and according to Mahabalipur Inscription of Rajendra I oliya nagas are of his period( 11th century AD.). So Purananooru is defintely 10th century AD to 11th century AD or later than that.
Here is an inscription belonging to one of the kings of the Irunkovel line from the Adhipuriswara temple in Tiruvorriyur district:
Records in the reign of the Ganga-pallava king Kovijiya Kampavarman, gift of 27 kalanju of gold for offerings by Pudi Arindigai, wife of Videlvidigu-Ilangovelar of Kodumbalur in Ko-nadu. The money was placed in the hands of the residents of Vaikattur, a suburb of Tiruvorriuyur, on interest at 3 manjadi per kalanju per annum
Kampavarman is dated to 870-900AD ,Irunkovel mentioned in Purananooru , so the date of purananooru has to be later than this date. Interestingly there was a dynastic struggle between Kampavarman(elder) and Nrputunga(boy) for the throne like Nedunkilli and Nalankilli
The dating gets even curious because the Purananooru mentions Pulikatimal (Hoysalas with emblem of Sala killing the Tiger that is Hoysalas ending the chola rule(Tiger Emblem)), who are of period 10th -14th Century AD . Interestingly it also says pulikatimal is from neighbhouring country. So if we take Hoysalas into picture, the date has to be after 11th century AD. Probably between 11th to 13th century AD. After which there was a intergennum because of Muslim invasion.
origin of Cholas
Date of Karikala
Date of Pallava
Myth of Tamil Sangam
Date of Silapathikaram