Gunpowder, or black powder, was first used in the Demon Spawn War (8972 GE - 9493 GE). It was used as hurled explosives, barrel bomb, and in breaking rock and against fortifications.
In the First Epoch, with advances in metallurgy, it began to see more common use in guns and artillery.
The Dulun of Ganuzdurak, future capital of the Deep Six, were perhaps the first to put gunpowder into widespread usage. They first created muskets then started making bigger things like cannons.
Deep Six and the Giff League are largely responsible for the spread of gunpowder armaments to the world Bal-Kriav and other worlds of the Quara'tun System.
By the Third Epoch, many of Bal-Kriav's holds had replaced their catapults and ballistas with cannons and mortars.