Conversation so far:
What was Garry Kasparov towards the top of?
He was at the top of the chess world.
When did Garry Kasparov reach the top of the chess world?
Kasparov became the youngest ever undisputed World Chess Champion in 1985 at age 22.

Question: What important matches did he play to reach the top?
Self-contained rewrite: What important matches did Garry Kasparov play to reach the top?