The website describes it best:
"To celebrate Philippe de Montebello's thirty-one years as director of The Metropolitan Museum of Art, the Museum's Forum of Curators, Conservators, and Scientists organized an exhibition of approximately three hundred works of art—from a total of more than eighty-four thousand—that were acquired during his tenure. This unique exhibition, which was on view October 24, 2008, through February 1, 2009, was a collaboration among curators from the Museum's seventeen curatorial departments. Special emphasis was placed on works that had been transformative to the Metropolitan Museum's collection by building on existing strengths and expanding into new areas."
The years in parenthesis are when the pieces were acquired.