Conversation so far:
Where is the team Ajax located?
Amsterdamsche Football Club Ajax, also known as AFC Ajax, Ajax Amsterdam, or simply Ajax, is a Dutch professional football club based in Amsterdam
was Frank de Boer a manager for Ajax?
he took over as manager of Ajax and went on to win the Eredivisie title in his first season.
What else did Frank de Boer do with Ajax besides management?
He won both the 1991–92 UEFA Cup and 1994–95 UEFA Champions League while at Ajax, in addition to five Eredivisie titles and two KNVB Cups.

Question: When was he hired as a manager?
Self-contained rewrite: When was Frank de Boer hired as a manager?