Conversation so far:
when did John Lee Hooker's career begin?
Hooker's recording career began in 1948.
What was his first recording?
The single, "Boogie Chillen'".
Was Boogie Chillen popular?
The single, "Boogie Chillen'", became a hit and the best-selling race record of 1949.

Question: what genre of music is it?
Self-contained rewrite: what genre of music does John Lee Hooker make?