Conversation so far:
What did he do with the Rolling Stones?
Taylor's onstage debut as a Rolling Stone, at the age of 20.
What year was that?
1969.
How long did he play with the Stones?
CANNOTANSWER.
What else happened during this time?
June 1969, John Mayall recommended Taylor to Mick Jagger.
What did Jagger say?
An impressed Jagger and Keith Richards invited Taylor back the following day.
What happened that day?
He overdubbed guitar on "Country Honk" and "Live With Me" for the album Let It Bleed.
How did the fans like the sound?
CANNOTANSWER.
Are there any other interesting aspects about this article?
Jagger stated: "We made [tracks] with just Mick Taylor, which are very good and everyone loves, where Keith wasn't there.

Question: Why wasn't Keith there?
Self-contained rewrite: Why wasn't Keith Richards there when the Rolling Stones was making tracks with Mick Taylor??