Focus on Morgan Casket and analyze the Similar pieces.
A similar casket exists in the Treasury of the Basilica of Saint Servatius in Maastricht, the Netherlands. The Maastricht Siculo-Arabic chest is smaller than the Morgan Casket but the carvings are almost identical, including the corner figures.
Another ivory casket in the Museum of Islamic Art, Berlin is more or less the same size as the Morgan Casket but misses both the 'balustrade' along the lower edge, and the corner figures. This casket is said to originate from Speyer Cathedral.
Various olifants in museum collections worldwide are carved similarly and may originate from the same workshop.
Treasury of the Basilica of Saint Servatius Maastricht Maastricht Siculo-Arabic chest Speyer Cathedral casket Museum of Islamic Art, Berlin olifants