A style of clay sculpture known as haniwa is associated with some of the grave mounds. The haniwa are earthenware pottery made of hollow tubes of clay. The subjects are abstracted humans of various occupations, farm animals, houses, boats, and other items. In ways they are similar in spirit to the clay items placed in graves in Han dynasty China. In some cases the inside of the larger tombs were decorated with murals, as seen in early China and Korea. By the fifth century, models of horses and bronze horse tack appear, along with more sophisticated metal swords, bows and arrow, and spears.