Complex sentence: In 1929, the Guelph Treasure was put up for sale by Ernest August, then the Duke of Brunswick, and was purchased by a handful of dealers, including Julius Falk Goldschmidt, Zacharias Max Hackenbroch, Isaak Rosenbaum, and Saemy Rosenbaum.
Split into simpler sentences: In 1929, the collection was put up for sale by Ernest August, then the Duke of Brunswick. Objects in the collection were individually purchased by a handful of dealers, including Julius Falk Goldschmidt, Zacharias Max Hackenbroch, Isaak Rosenbaum, and Saemy Rosenbaum.