Details seem rather hard to come by (partly because the endgame of the first K'ril incursion is my tabletop game, and that has yet to be played), but, outside of the Jedi Order, others with direct knowledge, and certain esoteric researchers, here's what's widely known
- ~85 years ago, a mysterious series of Mandalorian attacks on merchant shipping were traced to a technology-centric dark side cult known as the K'ril technomages
- A year after that, one of the leaders of the K'ril was traced to a huge battlestation under construction in an obscure system; the cult leader was killed, the plans retrieved, and the station destroyed before it was operational; it was widely believed at the time that the K'ril had been destroyed, or at least scattered
- Three years after that, a fleet of ships of unknown design, commanded by force-users and Mandalorians, began attacking Republic worlds in force
- After some time, it was discovered that the station destroyed earlier was a backup; they had already had a fully operational Star Forge at the time
- Eventually, between the efforts of the Jedi Order, the Republic Navy, and some independent operators, the true leader of the K'ril and what was generally regarded as Star Forge II were destroyed
- Most of the Navy the K'ril built -- or rather, hired the Mandalorians to build for them -- was absorbed into the Mandalorian clans after the K'ril were defeated