I have a theory that musicians recognize each other and if they are destined to collaborate together they will. Mainly, they recognize each other according to the class they belong to. If they are punk-rocker kids from the neighborhood, they are going form a band. If they happen to be musicians that are going to play in pubs and restaurants, they are going to recognize each other, form a band and play together. If it's about musicians that are playing jazz and are going to jazz festivals, for e.g., then they are going to meet and work together.