The names people have in a society can convey lot of information about their culture. Unfortunately this area has not been well researched in TN. The thalicheri kalvettukkal of Dr.Kalaikkovan is a rare exception - analyzing the names of 400 devaradiyars mentioned in the 55 Metre inscription of rajaraja.
In sangam period (almost you can all it a period of nobles and tribes) we find karikalan, killi, peruchotrudhiyan etc. Most of them were kaaranap peyar - names with reason not Idukurip peyar. Most were pure tamil names - though the influence of aryan gods like thirumal are already felt in literatures like paripaadal. Even god is called Iraiyanar.
Then kalabhras - Jain influence. Achudha vikranthan etc
Pallavas : Heavy sanskrit influence. Influx of the language over tamil. Later part of pallavas change this a bit. Names like varman becomes common. names of commonman unfortuately not recorded.
Early pandiyas : Sanskrit influence continues with mix of tamil - Srivallabha, srimara etc
Cholas : While tamil was held in due respect sanskrit did have influence. brahmins gaining lot of support. Rajendra period was the most notable period in which this power gained max prominance
Pandiyas ... Muslim invaders....
After this a transformation happens. Many people start having gods names as their names so that they can mention the god names. In early tamil land we do not find that many god names as human names - but now ? How many srinivasan, venkatesan, viswanathan?? How this transformation happened ? Was it a transformation at all ??