Rickshaws are commonly believed to have been invented in Japan in the 1860s, at the beginning of a rapid period of technical advancement.[2][3] In the 19th century, rickshaw pulling became an inexpensive, popular mode of transportation across Asia.[2] Peasants who migrated to large Asian cities often worked first as a rickshaw runner.[4][5] It was "the deadliest occupation in the East, [and] the most degrading for human beings to pursue."[5][nb 1] The rickshaw's popularity in Japan declined by the 1930s with the advent of automated forms of transportation, like automobiles and trains. In China, the rickshaw's popularity began to decline in the 1920s.[4][6] In Singapore, the rickshaw's popularity increased into the 20th century. There were approximately 50,000 rickshaws in 1920 and that number doubled by 1930.[7]