The earliest mention of the bronze is found in the epic called the Matsya Purana. The findings in the ruins of Mohenjodaro and the discovery of the figure of the dancing girl showed that the sculpture along with the use of metal alloys was well known to people of that period. The ancient treatise on sculpture, the Silpashastra tells us a story that captures quintessence of the art.

Casting

There once lived a king called Vajra. He was a pious and devout man. One day he found himself standing at the feet of sage Markandeya with a request. "Oh! Great sir, grant me but one wish," begged the king. "Teach me the art of iconography so that I may make my own idol for worship, using my devotion and yet another input." Though the sage appreciated King Vajra's sentiment, he was forced to ask him a few questions before handing him the first lump of metal. "Do you know how to paint?" asked the sage. The king did not, but requested that he may be taught it if that was a pre-requisite to learning sculpture. "But for that you need to know how to dance," insisted the sage. To learn dancing, in turn the king was required to have a rudimentary knowledge of instrumental music, which needed a foundation in vocal music. So the king had to begin with the octaves to be able to pour his sensibilities into any other material and make a form out of it. It is no surprise therefore that the beauty of Indian bronzes lies in their efficient capturing of all these artistic forms within the figure created. So close is the association that the different disciplines also share certain common terminology like the word tala. To a sculptor tala means one measure and to a musician or a dancer it refers to one beat, or the measure.

This unified aspect of culture is more than evident when one sees the fluidity of movement in these static figures. With Shiva (one of the gods of Hindu religious Trinity) symbolizing the cosmic forces of nature, dance becomes the epitome of life's rhythmic motion. The sthapathi or craftsman seeks to capture this motion in bronze. The contours of the legs, the arms and the whole body of a standing figure has so much of realism in it that one can perceive not only the previous stance but also the following one.

The evolved technique and the material used contribute to the magnificence of the end product in these bronze figurines. The conventions, rituals and instructions of measurements etc. are the same old traditional ones, which have come down through the ages.

While bronze iconography is age-old, it was only around the 10th century AD that there was a large-scale revival of this art form. Subsequently, within a few centuries, it reached its zenith. At this time, there was a strong religious fervor in the southern states following the waning of the influences of Buddhism and Jainism. The Chola reign saw many temples being constructed. The presiding deity was constructed in granite. But there was a need for more idols that could be carried around the village or town on festive occasions. These figures were called utsavamurthis. Granite was too heavy for this purpose and so came the alloy of five metals symbolizing the five elements. The metals were copper, brass and lead with a little bit of gold and silver.

Generally, deities are made from bronze. The favorite ones being Lord Shiva and his consort Parvati, Ganesha, the elephant faced one and Lord Rama, the incarnation of Vishnu. These are of course the more popular ones. However, there are innumerable variations upon the same theme, which capture every myth that is associated with the deities. After the Cholas, the degree of finesse seemed to fade away from this art and was never carried into subsequent generations though newer styles did evolve. The tradition has remained unbroken.

Source: http://india-crafts.com/metal_work/