The most recent exhibition at the Smithsonian’s Arthur M. Sackler Gallery, organized with help from the National Museum of African Art, Encompassing the Globe: Portugal and the World in the 16th and 17th Centuries, is as much a chronicle of history as it is a document for how art records history. Trying to pigeonhole this exhibition into a one category is difficult. It is more than just the fact the exhibition displays more than 260…