Cyalax was the planetary headquarters for Empress Shira during the rise of the Stellar Imperium and most of the Stellar Imperial War that began in 26 ABY and ended in 29 ABY. It remained the location of the hidden base of operations until Welk made a blunder and got captured on Yavin VIII. He was trying to infect the Jedi Knights hiding there with a virus that stripped them of their Force abilities by killing most off their midi-chlorians. Jaina Solo stole the information from Welk's navigational system and was able to flush Shira out of Cyalax.