Due to a recording ban during the crucial formative period of bebop Koko is considered by many to be the very first time Bebop was ever recorded, along with the Shaw 'Nuff session led by Dizzy Gillespie earlier in the year.
It is also one of the first of many contra-facts of Parkers. He had played Ray Noble's tune Cherokee so many times that by the end he hated it, but he had mastered the chords perfectly in all 12 keys. Koko has a partially improvised head and the chords are based on "Cherokee".
"I found that by using the higher intervals of a chord as a melody line and backing them with appropriately related changes, I could play the thing I'd been hearing."
These notes accompany the 1978 vinyl 5 album set of Charlie Parker: The Complete Savoy Studio Sessions.
A standard three hour/four side session was scheduled for November 26, 1945, at the WOR studios in New York for which Parker would supply original composititions. A Union contract was arranged the preceding week and Parker; Miles Davis, trumpet; Bud Powell, piano; Curly Russell, bass; and Max Roach, drums, were booked for the date. On the 26th Reig went to Parker's apartment to bring Bird to WOR and was informed the Powell had gone with his mother to Philadelphia where she was buying a house. No need to worry, however; Dizzy Gillespie was present and introduced to Reig: "Here's your piano player". Parker also had contacted pianist Argonne Thornton (later a.k.a. Sadik Hakim) ... and asked that he appear at the studio
There is dispute to this day as to who actually played piano and trumpet on each take of each track.
Miles Davis confirms in his autobiography that he did not play trumpet on Koko:
I remember Bird wanting me to play Ko-Ko, a tune that was based on the changes of Cherokee. Now Bird knew I was having trouble playing Cherokee back then. So when he said that that was the tune he wanted me to play, I just said no, I wasn't going to do it. That's why Dizzy's playing trumpet on Ko-Ko, Warmin' up a Riff, and Meandering on Charlie Parker’s Reboppers, because I wasn't going to get out there and embarrass myself. I didn't really think I was ready to play tunes at the tempo of Cherokee and I didn't make no bones about it.
Pianist Sadik Hakim, then known as Argonne Thornton, was also known to be present at the session, and some claim he played piano on Koko but this remains unconfirmed.