Kharavela of Kalinga records his conquest of a federation of Tamil kings in his Hathigumpha inscription, so the the antiquity of Tamil rulers is established.
You might see this statement everywhere in the net. The only other inscription apart from Ashoka edicts to date that mentions rulers south of Kaveri or Tamil Nadu. However the truth is far from this. Let us see first what is Hathigumpha inscription?
The Hathigumpha inscription("Elephant Cave" inscription), from Udayagiri, near Bhubaneshwar in Orissa, was written by Kharavela, the king of Kalinga in India, during the 2nd century BCE. Hathigumpha inscription consists of seventeen lines incised in deep cut Brahmi letters on the overhanging brow of a natural cavern called Hathigumpha in the southern side of the Udayagiri hill near Bhubaneswar in Orissa. It faces straight towards the rock Edicts of Asoka at Dhauli situated at a distance of about six miles.
The inscription is written in a type which is considered as one of the most archaic forms of the Kalinga brahmi alphabet, also suggesting a date around 150 BCE.
The inscription is dated to 165th year of the era of the Maurya kings, and the 13th year of Kharavela's reign, which, considering the coronation of Chandragupta in 321 BCE as the probable start of the era, makes a date of 157 BCE for the inscription, a date of 170 BCE for Kharavela's accession, and a date of 162 BCE for the conflict against the Yavana king Demetrius.
Let us see the Lines of the inscription where the said to be quoted.
(Line No. 4) done at (the cost of) thirty-five-hundred-thousands, and (he) gratifies the People. And in the second year (he), disregarding Satakamini, dispatches to the western regions an army strong in cavalry, elephants, infantry (nara) and chariots (ratha) and by that army having reached the Kanha-bemna, he throws the city of the Musikas into consternation. Again in the third year,
(Line No.11) .................. And the market-town (?) Pithumda founded by the Ava King he ploughs down with a plough of asses; and (he) thoroughly breaks up the confederacy of the T[r]amira (Dramira) countries of one hundred and thirteen years, which has been a source of danger to (his) Country (Janapada). And in the twelfth year he terrifies the kings of the Utarapatha with .................. thousands of
Many argue that line number four mentioning Musiks as mushikas of North Kerala. However that has been well established that they are the tribal people in North West India.
Scholar such as K A Neelakanta shastri argue the following ,Line number 17 show that there was a confederacy of Tamil kings and that was defeated by Kharavela. Let us see if it is possible.
1. Kharvela if he has to come south has to cross Satvahana country. I don’t feel Satakanni would have allowed that.
2. Kharvela not mentioning the crossing of Satvahana country is impossible.
3. No Tamil literature work, even if we accept that sangam work is of that period has shown any such event.
4. Tamira is copper, that is the only reason sirlanka is called Tampa panni, and there is no confusion over that. Even Mahabharata mentions only Dravida, not Tamira.
So the Tamira mentioned is not Tamila as said by Neelakanta Sastri. Tamira is somewhere else.
Where is the Tamira present?
You don’t have to look further than Bengal. This Tamira fits the bill, and there could be a confederacy of Copper traders here.
Tamralipta is the name of an ancient city on the Bay of Bengal corresponding with Tamluk in modern-day India. Tamralipti may have been one of the most important urban centres of trade and commerce of early historic India, trading along the Silk Road with China, by Uttarapatha, the northern high road, the main trade route into the Middle East and Europe; and by seafaring routes to Bali, Java and other areas of the Far East.  Origin of the Name Tamluk
According to some scholers Tamluk derives its name from the Sanskrit word Tamra Lipta meaning "Full of Copper".
Tamralipta (Tamluk), lower down the river Hooghly and sea port, had been an important waterway for more than 3000 years. It gets its name from the copper which was mined, as it is even now, at Ghatsila, Jharkhand, Orissa areas which are not far from the city. Copper had been eclipsed by iron around 100 B.C., so the name must have originated during the Copper Age, when Tamralipti exported the ore and metal to peninsular India; the alternative was the less accessible Rajasthan area. The longer, original name of the port was in use till the third century B.C., when Ashoka's daughter and son sailed from it for Sri Lanka.
According to local folklore the name Tamralipta came from the King Tamradhwaja (which means The King with Copper Flag/symbol) of the Mayura-Dhwaja (Peacock) dynasty. If you go according to Mahabharat's description the ruling period of the King Tamradhwaja is nearer to the end of the Copper Age. Probably this ancient king had a huge base of copper, and the metal brought prosperity to the region at his time. Thus both of the names -- Tamralipta and Raja Tamradhawja -- might have been originated from it.
Some early Vaisnav religious texts tell a facinating story about the origin of the name of Tamralipta. Once, when Lord Krishna was playing Maharaas in Vraj at Vrindavan Surya (Sun God) Dev rose from the east and accidentally saw Lord Krishna in intimate situation with his Gopis and Sri Radhika. Immediately Surya Dev had felt ashamed, became embarrassed and blushed a reddish copper colour like Tamra. And then Surya Dev again returned to the same corner of the east coast of Bharata and did hide (Lipta) himself in the Bay of Bengal. Where Surya Dev went back and hid himself is the place called Tamralipti.
History of Tamluk
This ancient port city and kingdom was bounded by the Bay of Bengal in the south, river Rupnarayana in the east and Subarnarekha in the west. The Rupnarayana is the joint flow of the river Dwarkeshwar and the river Shilai. The Bay of Bengal and these great rivers and their numerous branches created a prosperous and easy water navigational system fostering commerce, culture and early contacts with the people outside the region. At the same time, these rivers helped to develop the agriculture in this region.
Archaeological remains show continuous settlement from about 3rd century BC. It was known as Tramralipti (in the Purans and the Mahabharata) or Tamralipta (in Mahabharata) or Tamalika (in historical documents) or Tamalitti (in foreigners' descriptions) or Tamoluk (in the British Raj). It was a seaport, now buried under river silt. For this reason, Tamluk has many ponds and lakes remaining today.
In the Mahabharata (Bhishma Parba/Nabam Adhyay) while describing the names of the holiest rivers and kingdoms of India, Sanjay took the name of "Tramralipta" to Dhritarastra.
Tamluk was also known as Bhivas (in religious texts) and Madhya Desh (as the Middle State of Utkal/Kalinga and Banga).
According to Jain sources, Tamralipti was the capital of the kingdom of Venga and was long known as a port.
So the clever KA Neelakanta sastri has taken this reference to mean that it represents tamil. Even though being a distinguished Historian he should have known there is other Tamira nearby. No body including Bengalis have missed point. Kalingas are happy that their empire stretches to south India. Yet another attempt to stretch the antquity of tamil.