Conversation so far:
What did Charlie Parker do in his early career?
In the mid-1930s, Parker began to practice diligently.
What did Charlie Parker master?
During this period he mastered improvisation and developed some of the ideas that led to the later development of Bebop.
Did Charlie Parker work with anyone else of note?
1942 Parker left McShann's band and played for one year with Earl Hines, whose band included Dizzy Gillespie, who later played with Parker as a duo.

Question: What did they do together?
Self-contained rewrite: What did Charlie Parker and Dizzy Gillespie do together?