A black glaze used on straight-sided conical teabowls known as tenmoku ware *tenmoku jawan 天目茶碗. The glaze contains iron salts which turn black when they are oxidized in a kiln. If the iron content is low, a yellow-brown or liver-brown glaze called *ameyū 飴釉 is produced. If the iron content is high, it creates a red-brown glaze called *kakiyū 柿釉. It originated in China in the 11th-8th century BCE, and typifies Song dynasty, Jian ware kenyō 建窯 from Fujian Province.
Examples were brought to Japan in the Kamakura period by monks studying in China at the end of the Song dynasty, and were imitated, for example, in Seto 瀬戸 (see *setoyaki 瀬戸焼). By the Momoyama period, high-quality Japanese black glazes like kokkatsuyū 黒褐釉 (made in Seto), setoguro 瀬戸黒 and kuro-oribe 黒織部 (see *oribeyaki 織部焼) had developed. Tenmoku ware was used by the Japanese aristocracy for tea ceremony, and gradually, all black or black-brown glaze became known as tenmokuyū.