Conversation so far:
When did Thierry Henry return to the Bulls?
On 17 February 2012, Thierry Henry returned to Red Bulls to prepare for the 2012 season.
Why did Thierry Henry go back to the Bulls?
Thierry Henry's base salary of $5 million ($5.6 million guaranteed) made him the highest-paid player in MLS.

Question: When did he leave the Bulls originally?
Self-contained rewrite: When did Thierry Henry leave the Bulls originally?