Conversation so far:
When did Donnie Yen start martial arts?
At a young age, Donnie Yen developed an interest in martial arts and began experimenting with various styles. Yen then started kung fu when he was nine.
Who trained Donnie Yen?
Donnie Yen's parents were concerned that he was spending too much time in Boston's Combat Zone. They sent him to Beijing on a training program with the Beijing Wushu Team.

Question: How long did he train?
Self-contained rewrite: How long did Donnie Yen train with the Beijing Wushu Team?