According to historians, the more plausible theory is that ramen was introduced to Japan in the late 19th or early 20th centuries by Chinese immigrants living in Yokohama Chinatown. According to the records of the Yokohama Ramen Museum, ramen originated in China and made its way to Japan in 1859.
In December 1945, Japan recorded its worst rice harvest in 42 years, which caused food shortages as Japan had drastically reduced rice production during the war as production shifted to colonies in China and Formosa island. The US flooded the market with cheap wheat flour to deal with food shortages. From 1948 to 1951, bread consumption in Japan increased from 262,121 tons to 611,784 tons, but wheat also found its way into ramen, which most Japanese ate at black market food vendors to survive as the government food distribution system ran about 20 days behind schedule. Although the Americans maintained Japan's wartime ban on outdoor food vending, flour was secretly diverted from commercial mills into the black markets, where nearly 90 percent of stalls were under the control of gangsters related to the yakuza who extorted vendors for protection money. Thousands of ramen vendors were arrested during the occupation.
In the same period, millions of Japanese troops returned from China and continental East Asia from their posts in the Second Sino-Japanese War. Some of them would have been familiar with wheat noodles. By 1950 wheat flour exchange controls were removed and restrictions on food vending loosened, which further boosted the number of ramen vendors: private companies even rented out yatai starter kits consisting of noodles, toppings, bowls, and chopsticks. Ramen yatai provided a rare opportunity for small scale postwar entrepreneurship. The Americans also aggressively advertised the nutritional benefits of wheat and animal protein. The combination of these factors caused wheat noodles to gain prominence in Japan's rice-based culture. Gradually, ramen became associated with urban life.
In 1958, instant noodles were invented by Momofuku Ando, the Taiwanese-Japanese founder and chairman of Nissin Foods. Named the greatest Japanese invention of the 20th century in a Japanese poll, instant ramen allowed anyone to make an approximation of this dish simply by adding boiling water.
Beginning in the 1980s, ramen became a Japanese cultural icon and was studied around the world. At the same time, local varieties of ramen were hitting the national market and could even be ordered by their regional names. A ramen museum opened in Yokohama in 1994.
Today ramen is one of Japan's most popular foods, with Tokyo alone containing around 5,000 ramen shops, and more than 24,000 ramen shops across Japan. Tsuta, a ramen restaurant in Tokyo's Sugamo district, received a Michelin star in December 2015.