Complex sentence: In 1969, Brezin co-founded the Circle Repertory Company, along with Wilson, Mason, and Thirkield; the theatre helped to develop many actors, directors, and playwrights.
Split into simpler sentences: In 1969, Brezin co-founded the Circle Repertory Company, along with Wilson, Mason, and Thirkield. The theatre has helped to develop many actors, directors, and playwrights.