Until the end of the Imperial China the four character phrase Wan Shou Wu Jiang was reserved for the birthdays of the emperors and empresses of China. The phrase translates as 'may you have ten thousand longevities without boundary'. Many similar interpretations seem to exist such as 'Ten thousand years of boundless longevity'.
Wanshou wujiang, literally 'countless years of long life without limit' comes from the Shijing (Book of Odes or Classic of Poetry), comprising poems and songs dating from the 11th to the 7th century BC, and traditionally believed to have been one of the 'Five Classics' compiled by Confucius (551-479 BC).
From as early as the Song dynasty, the birthday of the emperor was known as the Wanshou jie (Festival of Ten Thousand Longevities), and in the Ming and Qing dynasties it was one of the major annual festivals of the Beijing court.
Shou longevity characters appear on underglaze blue decorated porcelain as early as the Yuan dynasty. A Yuan dynasty blue and white stem bowl with flying phoenix on the exterior and a shou character on the interior, excavated in 1972 in Hebei province, was included in the Beijing Capital Museum exhibition Blue and White of the Yuan, Beijing, 2009, p. 109-111. In the published examples, only a single character appears, usually on the interior of the vessel.
Multiple shou characters were used to decorate blue and white porcelain in the middle Ming period. A blue and white Jiajing mark and period (1522-66) jar and cover with a design of shou characters in roundels each supported by a lingzhi fungus on a scrolling vine in the Palace Museum, Beijing illustrated in The Complete Collection of Treasures of the Palace Museum - 35 - Blue and White Porcelain with Underglaze Red (II), Hong Kong, 2000, p. 115, no. 105.
Indeed, all manner of iconography related to longevity was applied to porcelain during the Jiajing period, as in the latter part of his reign the Jiajing Emperor became obsessed with the notion of immortality.
Similar blue and white jars, albeit with shou characters which are larger and completely fill the roundels, were also made in the Wanli reign (1573-1619). A Wanli jar and cover of this type was excavated in 1971 from the Dongcheng district in Beijing (illustrated in Wenwu, 1972, no. 6, inside cover, fig. 3). However, in the Kangxi reign of the Qing dynasty the use of shou characters appears to have become even more popular on imperial wares and large wanshou vases with up to 10,000 characters were made.
It is generally believed by scholars that the so-called Kangxi 'birthday plates' decorated in fine overglaze famille verte enamels, which have the characters wanshou wujiang included in their characteristic iron-red brocade-style border decoration were made for the 60th birthday of the Kangxi Emperor in 1713, the 52nd year of his reign, possibly to be given to especially favored guests on the occasion of the 'grey beards' banquets.
During the Tongzhi period (1862-74) at least two series of porcelains with this phrase seems to have been ordered for the wedding of the Tongzhi emperor in 1872. (Longsdorf,R.W., Orientations, October 1996). Either that, or that the porcelain in reality was ordered for a birthday. In 1874 for example, the Empress Dowager Cixi would have been 40.
The decoration appears to enjoy a revival around the Guangxu period (1875-1908) and becomes popular at the time of the Early Republic. A popularity that remains until today.
In a shortened version the same phrase (wanshou - ten thousand longevities) can be referred to in decorations by combining the swastika (wan) with the shou character.