India was home to Saltpeter(gunpowder); the production peaked during the British rule

saltpter production, India
.Saltpeter production, colonial India.
Figure 1. Firing cannons on the fort wall of Sri Rangapatna (Karnataka) -  a caricature featuring Charles Cornwallis’s battlefield reverses at Sri Rangapatna, Mysore. James Gillray,
1791, published by H. Humphrey, London;

'Violence',  never played a part in the earliest human civilization, however the early people encountered violence from the Nature in the form of storms, deluge, etc  and  wild animal on prowl. Violence slowly crept  into the early civilization  due to hostile environments. Life threatening  human traditions  became facts of life, down the centuries. Instead of using  stones, sticks and swords,  man began to understand the value of fire in war fare and in defending his territory. Then came the gunpowder, artillery guns cannons, etc  that dominated till the end of 19th century. Saltpeter was the earliest ammunition used by men during big battles in the later centuries. India was the major producer of this stuff which had been widely used as a medicine in the way past for curing certain ailment. 
East India company
What is special about saltpeter? Why did India play such an important role in saltpeter  production?  Saltpeter is actually potassium nitrate – also known as niter,  it was a necessary ingredient for gunpowder  and in manufacturing modern fire crackers; the other ingredients being  charcoal and sulfur.  Way back India developed special methods  and  had perfected the method of making  potassium nitrate (KNO3). 

India  accounted for the largest gunpowder production system in the history of the world and it sustained the status  till  the 20th century. In particular, in the state of Bengal and Bihar gun powder production was quite high  taken care of by a specified caste called the nuniah.  Saltpeter beds supplied the most vital element in gunpowder  and India produced virtually all of it. Besides above , saltpeter was manufactured in other places like kurnool, Anantapur, Guntur (composite Andhra), Agra (UP), Coimbatore (Tamil Nadu) and certain parts of Karnataka (Mysore). 
The Guntur Sircar accounted for large scale commercial  production of saltpeter. In the other parts of the world in the middle of the 17th Century  only a small amount of  saltpeter using  calcium nitrate, a hygroscopic salt, which would get spoiled seasily by absorbing moisture from air, according to the 17th century Royal Society paper  on Saltpeter production in India.   
saltpter production on industrial scale, india 17th century?
When the East India company wanted to stay permanently in Bengal by way of expanding their mercantile trade operation and also encouraging illegal trade activities through proxies  during the reign of Siraj-ud Dualah,  the Nawab of Bengal, they were already in saltpeter production. The Armenian merchants and also  the notorious wheeler and dealer of Calcutta and famous financier Omichund, made a bundle in the saltpeter trade in this region. At one point of time Omi Chand in collusion with the Nawab's relatives helped the EIC led by Robert Clive win the decisive war -  the Battle of Plassey in Bengal in order to topple Siraj who was later murdered at the instigation of the British. The victory is a mile stone in British India history that tipped the scale in favor of the English company and its successful operations in India. In the later years, with vast revenue from Bengal and other places, India became Britain's '' Cash Cow''. The British economy got a big boost and its GDP rose from mere 2.5 to more than 20  when they left India for good in 1947. 
EIC and its cronies like Omi Chand exported large quantity of  saltpeter (potassium nitrate) to other countries. The complete take over of Bengal with rights to collect revenue (Firman), put the company on a strong base and the British controlled  over 70 percent of the world’s saltpeter production during the later part of the eighteenth century. 
The paradox is there was fairly a continuous demand for saltpeter from various quarters.  The powder stocks could not be prepared  or  made easily. So, during peaceful time  gun powder was more in demand than normal to build up stocks /reserve in case of sudden military confrontation or local emergency like riots, etc.  

China developed fireworks, rockets, and other incendiaries rather than shot-firing artillery  because of its  reliance on artificial saltpeter for making gunpowder. The Chinese often used a higher proportion of charcoal and sulfur, which resulted in more fire power and less ballistic strength.  The difference between India  and China was the former  produced saltpeter of very high quality, enabling the development of gunpowder based weapons, in particular heavy siege guns, in addition to rockets. In the case of latter - China more mixing of charcoal and sulfur resulted in more fire power, and less ballistic application -  the strength was not good enough for military application. So, for  application to military purposes, the countries preferred  more advanced  Indian gunpowder to that of China that lacks  ballistic strength.   

Saltpeter production in India had been there for a long time before the advent of EIC. In 1460s the rulers of Jaunpur and Bengal already had organized saltpeter production as state monopolies managed by their chief merchants  from Iron according to Iranian sources.  The gunpowder was not shipped to India from Europe in any significant quantities.  A little known fact is with respect to gunpowder technology and its infra structure development, India was far ahead of  Western Europe -  roughly a century ahead.   

Yet another interesting fact is the saltpeter trading activities in Rajapur were controlled by Saraswat Brahmins, with investors from as far off places such as  Goa and Diu.  By 1617, the Portuguese king  showed keen interest to procure saltpeter like other European countries. However, Chatrapati Shivaji (r. 1664-1680) and later his successors had a state monopoly in the saltpeter procurement, thus forcing the Portuguese, their Indian agents, and Banjara peddlers to deal with the Maratha state for their needs. 

During the  Mughal Empire, guns and artillery, the symbol of imperial played a great role in their battles.  It was the careful handling of artillery  firing that helped  Babur (r. 1526-1530) emerge victorious over his battle with  Ibrahim Lodi (r. 1517-1526). The successors of Mogul rulers kept using artillery power during confrontation and came up with some improvement in firing power and range. Through out the Muslim rule in India saltpeter production, particularly in the plains of Ganges, continued without any break till the reign of Sher Shah  (r. 1540-1545) who himself was killed during gun powder explosion. 

The British became a global power after gaining hegemony in India for two good reasons - 01. Huge  revenue from the Indian lands, Indian produces, etc, 02. The British control over  Indian saltpeter trade,  engineered  the military revolution and the rise of Britain as a global superpower.  Later Saltpetre exports were banned by the English company and the irony was  the wily English dexterously handled the gunpowder production  to subjugate Indian rulers and natives.
In 1780, saltpeter was produced in France to cut down the British monopoly in Europe. During the civil war in America  EIC manupupated the political turmoil there  by being neutral  and supplied Salpeter to both Northern unionists and Southern Confederates. This way  they they made money at both ends.