Though Sangam literatures throw some light on how the people lived during sangam age, there are not enough proof other than literatures to understand their way of life. This is mainly no excavations were done in Tamilnadu,like Harappa or Mohenjodaro . There are some links between tamil civilization and other well known civilizations.But those are not enough. Until there is a major excavation in Tamilnadu, it would be hard to prove that there was a tamil civilization before sangam age.
I actually agree with the theory that people moved from northern India to southern India. The move might have taken a long long time and in this case, Did the migrated people bring the whatever culture they had it in other civilization? or Did they form a new civilization?. This migration could not have happened over night. So Defnitely people brought few customs along with them and formed a new civilization. So when that would have happened? It should be definitely before sangam age. The mighty king Asoka did not conquer Tamil land during his time(300 BCE) and maintained friendly relationships with the tamil kings. That means that some form of civilization should have been in Tamil land at that time and it should have taken at least 1000 years to form a governed society. So during 1000 BCE at least, tamil land should have a civilized society.
Indus Valley period (3500 BCE)
- In May 1999, 'plant-like' and 'trident-shaped' markings have been found on fragments of pottery dating back 5500 years at Harappa (Pakistan). This is the earliest script identified till now and these scripts are older than the scripts found at Egypt and Mesopotamian civilizations.
- A well-preserved bull-fighting seal found at Mohenjodaro in the 1930s. It’s 2000 years old seal. Is it the proof that Dravidian culture migrated from Indus valley? Tamilnadu is the only place in India where bull-fighting is still practiced.
- The arrow-mark graffiti on the megalithic pottery found at Sembiyankandiyur and Melaperumpallam villages, Nagapattinam district. As they are in the Indus scripts, arrow-mark graffiti are always incised twice and together. Indus script belongs to the period 2600 BCE to 1900 BCE.
- A large megalithic terracotta plate found at Sulur near Coimbatore, with symbols closely resembling an inscription on a tablet found at Harappa.
- Excavations at Mayiladuthurai have been claimed to contain Indus symbols being used as late as 1100 BCE.
- The urn with the rudimentary Tamil-Brahmi script, and a human skeleton and miniature pots at Adichanallur in Tamil Nadu, dated back to 500 BCE.
- Three foot Hero stones of the Sangam era found at Puliyamkombai in Andipatti taluk of Theni District. These are the oldest among the hero stones in India so far. These stones are 2300 years old, roughly belong to 300 BCE.
- Jambai inscription proves that the “Satyaputo” mentioned by Asoka was none other than the Adhiyaman Neduman Anji dynasty, which ruled from Tagadur, modern Dharmapuri.
- Mankulam inscription of Pandyan king Nedunchezhiyan
- Chera King Irumporai inscriptions at Pugalur near Karur
- The Pandyan coin of Peruvazhuthi or the silver portrait coins of Cheras belong to Sangam age.
- Numerous gold, silver and bronze rings of merchants and noblemen from the prosperous trading town of Karur dated back to Sangam period.
- A broken storage jar with inscriptions in Tamil Brahmi script dated to first century CE, excavated at Quseir-al-Qadim, an ancient port with a Roman settlement on the Red Sea coast of Egypt. Earlier 30 years ago, two pottery inscriptions in Tamil Brahmi belonging to the first century CE found at the same place. Another Tamil Brahmi pottery inscription of the same period was found in 1995 at Berenike, also a Roman settlement, on the Red Sea coast of Egypt. These discoveries provided material evidence to corroborate the literary accounts by classical Western authors and the Tamil Sangam poets about the flourishing trade between the Tamil country and Rome (via the Red Sea ports) in the early centuries CE.
- A unique Tamil-Brahmi Inscription on pottery of the second century CE has recently been excavated in Thailand. And also a touchstone engraved in Tamil in the Tamil-Brahmi script of about the third or fourth century CE found in Thailand. This indicates that the overseas trade between India to both the West and the East involved people from the Tamil country.