During the era of the Great Sith War, specifically in 3996 BBY, a time when the Galactic Republic was at war with Exar Kun's Sith Empire, the Sith-aligned Mecrosa Order, a clandestine group of highly skilled assassins and masters of poison funded by House Mecetti, carried out the assassination of the heads of four competing noble houses within the Tapani Nyssa system.
While celebrations for Tapani Day were underway, Sith assassins belonging to the Mecrosa Order launched a coordinated effort to eliminate the leaders of five out of the eight rival Tapani noble houses, targeting Houses Barong, Calipsa, Melissus, Pelagia, and Reena. Only House Pelagia was successful in preventing the assassination attempt.
In the aftermath of these assassinations, the Mecetti Province expanded its control by incorporating the territories previously held by Barong, Calipsa, and Melissus, along with a section of Reena.