The Mauryan kings were 'shy' men. When their Greek contemporaries such as Vima Kadphises and Demetrius, who ruled Gandhara and Bactria, issued coins showing their image, the Mauryans who ruled from the Gangetic plain from 4th to 2nd century BC, issued coins with simple punchmarks on them. All the same, the coins of Chandragupta Maurya, Bindusara, Asoka, Brihadratha and others were pieces of art in their own ways. Their coins were mostly silver, bearing punchmarks, and weighed 3.2 grams. A rare one would bear a picture.
The Guptas, who ruled from the 3rd to 5th century AD, weren't as shy. Some of them lent their images to their coins. So we have seen the mighty conqueror Samudragupta sitting with his veena, and Chandragupta II, the supposed Vikramaditya, with his Lichchavi consort Kumaradevi. The Guptas made coins from metal billon—an alloy of mostly copper and a small quantity of silver.
The Tomaras who set up the first known kingdom in Delhi made coins hammered and pressed. Anangapala Tomara who ruled from 1049 to 1079 introduced his own stamped crude coins using hammer to press the plates. The coins were irregular in shape and flattened with mounted pressure.
Unlike today's mint coins, which have standard shape, image and inscription, the 'pressured' coins differed from one another. In 1145-1167, Madana Pala II introduced fresh handmade coins that varied in technique. The Chahamanas or Chauhans of Shakambhari also issued coins in billon which weighed 3.2 grams.
The Islamic rulers introduced coins with Quranic inscriptions, but the first Muslim ruler of Delhi, Muhammad Ghori, issued a coin depicting Goddess Lakshmi. Coins of this period were made using metal billon and bore horse-and-bull patterns. Qutubuddin Aibak, who succeeded Ghori, did not introduce new coins despite acquiring his empire. He carried forward the legacy of Ghori's coins.
But the arrival of the slave or Mamluk dynasty with Qutubuddin Aibak saw a major transformation in coins—they issued coins in precious metal. During Alauddin Masud's period (1242-46 AD), gold, silver and billon coins became widespread. While gold and silver coins were issued from Lakhnauti and Delhi, billon coins were struck from both Badaun and Delhi.
Perhaps the most famous, or notorious in India's numismatic history is Muhammad bin Tughlaq who ruled from 1325-51 CE and conquered up to the southern tip of Karnataka and Madurai. He knew the importance of currency for trade and he took keen interest to circulate gold and silver coins. The gold coin was introduced as dinar and silver coins were named Adl. However, he soon found that he could not maintain their supply for long on a large scale. So, he replaced those coins with copper and brass coins, but giving a higher face value. The copper coins weighed 3.3 grams. Soon counterfeiting started and the sultan had to demonetise the cheaper metal coins. Firoze Shah, the last prominent sultan of the Tughlaq dynasty, too issued coins in gold, silver, copper and billon.
The eclectic Mughals refined coinage further with copper coins that weighed upto 20 grams. While Akbar issued coins depicting Ram and Sita, Jahangir imprinted zodiac signs on some of them. His son Shahjehan's coins were calligraphic. Coins made during Shahjehan's son Auranzeb's empire were mostly in copper.
Much of these, and more about how history was 'minted' in India, can be learnt from the National Numismatic Exhibition, which has been mounted by National Numismatics Society in Delhi's All Indian Fine Arts and Crafts gallery. A rich horde for coin-collectors and history-buffs.