There is evidence that the metal bell originated in China, with the earliest known Shang dynasty (16th–11th centuries BCE) bells being among the oldest bronze objects found in China. They possibly originated from grain scoops of standard capacity (the word "chung" or grain measure is used in many ancient texts to mean a bell). Early bronze standing bells called "nao" embody some of the highest technical skills of Chinese civilisation and represent the earliest known form of chiming bell. Taking the shape of hollow-stemmed goblets with a curved rim, "nao" were made in sizes varying between 8 and 50 cm. They were mounted on their stem, with rim uppermost, and struck on the outside with a mallet. "Nao" from southern China were produced as single specimens, while in the north they were produced in chimed sets of three. Some were constructed such that striking at two different points would produce different ringing tones.