http://tamilartsacademy.com/articles/article08.xml Dr Nagaswamy dates Andal to later half of 8th century based on his identification of the Pandya referred by Periyazhvar as Srimara Srivallabha. Since Azhvar calls him as Nedumaran while guruparampara texts call the king as Vallabhadeva. Srimara fits both

This makes sense when viewed normally. But there are some other problems which crop up with this date. Primarily, Andal mentions a unique astronomical event in Tiruplavai - on Margazhi full moon day, Venus rose while Jupiter set before sunrise. This happened in 731 CE & the 886CE

Now, if we consider 886 CE as date of Thiruppavai, we fall into multiple problems. By this time, Pandyan power had been destroyed at Tirupurambiyam by Aditya Chola. Parantaka Viranarayana who ruled at this time was not strong enough to visit Chola dominions

unlike his elder brother who visited Chidambaram earlier (said brother lost the battle). Varaguna II, his elder brother, was shishya of Manikkavasagar. He was reigning supreme till 885 CE when Cholas and Pallavas along with Gangas destroyed Pandyan power.

Andal is said to have visited Srirangam with Pandyan ruler when she married Ranganatha - as per tradition. This doesn't seem possible post 885 CE. But this is not primary issue. Periyazhvar himself alludes to his daughter being taken away by Vishnu as His bride - after 886 CE

And his mentioning of Nedumaran as reigning Pandyan monarch happens AFTER his mentioning abt Andal becoming Vishnu's bride - during his last days at Tirumaliruncholai. It cannot refer to Srimara. Parantaka Viranarayana is not titled Maran in any primary sense.

If you consider the ruler to be Maravarman Rajasimha (who lost his kingdom to Cholas in 920 CE), he was a weak ruler who was unfit for the praise given by Azhvar. And if he lived in Rajasimhas time, then he could not have visited Srimara Srivallabhas court before 862 CE

Royal names used in later Guruparampara texts cannot be taken seriously because be it Periya puranam or Vaishnava hagiographies, they never use the primary titles of the kings. After all, rulers r not very important as this is not history. So, it is better to use primary texts

What we know is that Azhvar mentions about a Nedumaran (the prefix Kon simply meaning king) who ruled Pandyadesha after his daughter had married Vishnu. His daughter mentions an astronomical event which was possible in 731 CE and 886 CE. 886 CE doesn't fit the scheme.