The Wolhanian expedition was an archaeological mission to the moon Yavin 4 that took place sometime before 19 BBY. The Argazdan scientist Doctor Raygar was a member of the expedition. At some point afterward, Raygar became obsessed with locating mystical artifacts and lost respect in the academic community.
The group studied the Massassi ruins and uncovered the Massassi frieze, an ancient Sith Chalice and other Sith-related artifacts. Both the frieze and the chalice became part of Supreme Chancellor Palpatine's private art collection at some point before 19 BBY.