Complex sentence: The beginning of the evolution of the "mambo section" from montuno is attributed to Machito and his Afro-Cubans, who included material, new to Afro-Caribbean music, for brass and saxophones, borowed from the big band.
Split into simpler sentences: The beginning of the evolution of the "mambo section" from montuno is attributed to Machito and his Afro-Cubans. They included material, new to Afro-Caribbean music, for brass and saxophones, borowed from the big band.