The Solari wars were a series of conflicts fought between factions on the planet Solari for fifteen centuries. By 2365, the conflict had become personal and the original cause for the wars had been largely forgotten. One of the historic battles of these wars was the Battle of Zambrano.
In 2365, the factions came together and requested a mediator from the Federation to end the conflict. Riva was the mediator chosen; after the death of his chorus by a Solari who was distrustful of the negotiations, Riva would attempt to solve the conflict by first teaching the faction leaders sign language. By learning this language, it was hoped the factions would come to learn how to live in peace. (TNG: "Loud As A Whisper")