Complex sentence: In 1938 he teamed up with pianist Bill Doggett's group, and by 1940 had formed a completely new orchestra, which included Doggett and drummer "Panama" Francis.
Split into simpler sentences: In 1938 he teamed up with pianist Bill Doggett's group. By 1940 had formed a completely new orchestra, which included Doggett and the drummer "Panama" Francis.