The Black Sun - Exchange War was a struggle for control of the Coruscant Undercity by two of the galaxy's most powerful criminal organizations, the Black Sun and The Exchange. The initial conflict grew over failed negotiations on Vjun seeking to set the bounderies of each criminal faction's control of the spice trade. Much of the responsibility for the breakdown of negotiations is laid at the feet of then Black Sun Overlord Cayce Urriah, who took an instant and intense dislike for Exchange crime boss Hulio Andel.