Date of Tamil Saints

Currently, I am involved in dating the period of Andal and Manickavacagar. Sri M. Raghava Iyengar has dated Andal's period as the early 8th century AD(to be more specific, her composition of Tiruppavai in 731 AD). He claims to have done so, based on the astronomical sightings reported in Tiruppavai. But there are some anomalies in his findings.

Similarly, the date of Manickavacagar is also controversial though he is generally believed to have lived in 9th century AD.

I think i will post my views on this subject within a week.