Saltpeter, also known as potassium nitrate (KNO3), is a chemical compound commonly used in gunpowder, fireworks, and fertilizer. It occurs naturally in the form of mineral deposits called niter. Saltpeter has been utilized for centuries in various cultures, with early records of its extraction dating back to ancient China and India. Its role in gunpowder production was particularly significant, as it acted as the oxidizing agent necessary for combustion. During the Middle Ages, saltpeter became a valuable commodity, and its extraction and production were closely guarded secrets of various military powers. Beyond its military applications, saltpeter has been used in agriculture as a nitrogen-rich fertilizer to enhance plant growth. However, due to its potential to contribute to environmental pollution and groundwater contamination, its use in agriculture has become more regulated in modern times.

References: - https://en.wikipedia.org/wiki/Saltpeter