When the European "East India Companies" (EIC) set up trading posts in India in the early 1700's they used locals to augment their small forces. The Dutch called them "Peons" (countrymen). These men were untrained locals led by local Zemindars or other local rulers. They would be equipped with any of the following: matchlocks, swords , spears and/or shields.
The sculpt's below are based off of the print in Osprey Men at Arms #453 - Armies of the East India Company.
These can be used from 1700 up until the mutiny. They could also serve several purposes beside Sepoys - like Indian Pirates, Bad mashes, Darkest Africa mercenaries to name a few. They could augment any Indian force (Mysore, Mahratta, Mogul, Rajput etc) as irregulars or even Princely Sepoys.
Getting closer to production....