Since their grueling campaign against the Nevoota, the Mandalorians had only grown in power, cutting a swathe through the galaxy in search of worthy opponents. When the Mandalorians besieged the planet Basilisk, the Basiliskans‒reptilian droid-builders and legendary technologists‒learned that the stories of Mandalorian battle prowess were true.
Realizing they couldn't win even with Republic aid, the Basiliskans chemically poisoned their own world, hoping to take their conquerors with them. But the Mandalorians were victorious nonetheless, enslaving the Basiliskans and eventually turning them into mindless beasts of war.
More importantly, the Mandalorians captured many of the unique droids that the Basiliskans created. After this conquest, they were able to mass-produce the droids for themselves. Centuries later, the Mandalorians' Basilisk war droids would become a legendary terror during the Mandalorian Wars.