The Demonic Infiltration started in 120 PR.
Background
Starting with Realm War I, the kingdom of Troverth began experimenting with summoning and controlling Demons as a way of fighting wars with other kingdoms. The idea would catch on over the next century, and soon summoning Demons became a powerful alternative to magical warfare.
However, as more and more demons were being summoned to the realm, it would attract the attention of "Demon Lords" who had long since abandoned plans of taking over Quelmar after being driven out by the Pact Primeval in prehistoric times.
About
At some point, the infiltration had reached Jewelspar, leaving many citizens with a high paranoia and sensitivity about topics related to demons.
Ending
Traveling to his lair, a group of world saving heroes would kill Demogorgon, formally ending the Demonic Infiltration.
