Balances for weighing articles of trade were of two kinds. One was the steel-yard called ñemankōl or niṛaikōl, this was made of wood and resembled the steelyards used in villages to-day; rich merchants, however, used steelyards made of ivory. The second was the tarāśu, a pair of scales. All this trade was carried on by barter, as old Indians did not like to coin metal, and when they got coins from foreign countries, made jewels of them for their bosoms or hoarded them deep in the bosom of mother-earth.
Traders, in the Tamil country, were and are called  This word has been sanskritized into śreshṭhī and assimilated to the adjective śreshṭha, excellent. Śreshṭī is by some supposed to have degenerated into śeṭṭi; I consider this derivation to be a topsy-turvy one. Śeṭṭi is the personal noun from śeṭṭu, trade, a śeṭṭi being one who pursues śeṭṭu, trade, as his profession; for it is absurd to think that the Tamil traders carried on their profession for ages without a name for their profession or for themselves as followers of the profession. Hence it is reasonable to infer that śreshthi is Tamil śeṭṭi dressed in a Sanskrit garb. Sanskrit scholars suffer from a form of superiority-complex and believe that Sanskrit, the language of the Gods, being a perfect language, could not stoop so low as to borrow words from the languages of men. Hence they are fond of inventing derivations, ingenious and plausible, but absurd from a historical point of view, for words borrowed from foreign sources. Thus they say that hammīra, borrowed from Persian amir, is a contraction of aham vīrah; they explain kshatrapa, satrap also borrowed from Persian, as kshtram pātīti kshatrapah; they derive horā, which was borrowed from Greek, from ahorātram, with its head and its tail amputated. The derivation of śeṭṭi from śreshthī is of a piece with these products of a perverse ingenuity..
The capital with which the ancient traders traded was called mudal, initial stock. I wonder whether mudaliyār meant originally men with mudal. There has always been a rivalry between mudaliarmm and piḷḷai with regard to social status; does this point to an ancient rivalry between merchants and agriculturists? We have no materials which can help us to solve this question. Literary evidence merely indicates that both those who produced crops and those who sold them belonged to the class of mēlōr, who were qualified to become the heroes of love poems.
Trade on any scale would scarcely be possible without debts. The word kaḍan shows that debts were contracted in olden times. Interest was called vaṭṭi, a word usually identified with prakrit vaḍḍi Sanskrit vriddhi. The Tamil word might as well be derived from Tamil vaṭṭu, a small piece, or vaṭṭi, cowries, cowries being small change, sillaṛai. Vāśi meant a deduction other than vāṭṭi; the literal meaning of the word seems to be 'additional'. The places where mercantile transactions took place were kaḍai, maḷigai, aṅgāḍi, and sandai,  which has become in English 'Shandy'.
யானை வான்மருப் 'பெறிந்த வெண்கடைக்
சோனிறைத் துலாஅம்.Puṛam 39.