Final answer:
The medium of the plaque from the Kingdom of Benin featuring the Palace and Attendants is brass, made by local artisans using the lost-wax casting method during the sixteenth century.
Step-by-step explanation:
The medium of the plaque featuring the Palace and Attendants from the Kingdom of Benin is brass. These brass plaques were created by the artisans of Benin during the sixteenth century to adorn the royal palace. The art of casting brass and bronze in Benin reached sophisticated levels and was done using the lost-wax casting method. This technique involved creating a clay core, which was then coated with wax. The wax was then carved with detailed designs. Once the wax mold was ready, more clay was used to encase it. When the mold was heated, the wax would melt away, leaving a cavity into which molten brass or bronze could be poured, creating the final sculpture. The plaques were not only decorative but also depicted historical narratives and glorified the Oba, or ruler. As historical artifacts, they portray the opulent lifestyle of the rulers and offer a glimpse into the interactions with European merchants, as well as the local culture and governance of the time.