Dominoes spots from one to six are generally arranged as they are on six-sided dice, but because blank ends having no spots are used, seven faces are possible, allowing 28 unique pieces in a double-six set. However, this is a relatively small number especially when playing with more than four people, so many domino sets are "extended" by introducing ends with greater numbers of spots, which increases the number of unique combinations of ends and thus of pieces. Each progressively larger set increases the maximum number of pips on an end by three, so the common extended sets are double-nine, double-12,
Chinese dominoes of dominoes in China comes from the "Former Events in Wulin" (i.e. the capital Hangzhou) written by the Yuan Dynasty (1271–1368) author Zhou Mi (1232–1298), who listed ""pupai"" (gambling plaques or dominoes) as well as dice as items sold by peddlers during the reign of Song Emperor Xiaozong (). Andrew Lo asserts that Zhou Mi meant dominoes when referring to "pupai", since the Ming author Lu Rong (1436–1494) explicitly defined "pupai" as dominoes (in regards to a story of a suitor who won a maiden's hand by drawing out four winning "pupai" from a set). Tiles dating from the 12th