Benin art is primarily based around a court context, and was designed to venerate the achievements and/or memory of the Obas, the divine rulers of the Benin polities. The artists and craftsmen were typically attached to a specific court, and charged with manufacture of objects solely for their ruler. Their work in bronze and copper, ironworking and sculpting in a range of materials that particularly included ivory was extremely refined and effective; indeed, smelting, forging and cire perdue (lost wax) metalworking methods exceeded any seen in Europe until the 19th century. Obas were immortalized as one or several bronze/brass heads, which were used as supports for holding elephant tusks in a crescent across the top of commemorative altars. Brass leopards, spears, statues, tableaux (depicting the Oba and his followers) bells (to awaken the spirits) and rattle-staffs (ukhurhe) are also known, although it is perhaps for the famous brass plaques that Benin artistic heritage is best known. In them it is possible to read the history of the Benin peoples, from the earliest kings to the arrival of the Portuguese explorers in the 15th century, to lion/leopard hunts and war scenes, populated by the Oba and his family, regal attendants, musicians, soldiers, noblemen and priests.