It is generally believed the Japanese race was formulated from multiple ethnic groups, with a strong influence from so-called "hunting people." The prohibition of a meat diet, however, was not a result of the dissemination of Buddhism, but was because of orders from the rulers at the time. Animal meat and milk are ideal protein sources for humans, which most likely contributed to the physical buildup and stamina of caucasians. Many heroes in the Japanese warring states period including Iyeyasu Tokugawa, Soun Hojo and Motonari Mori lived long with numerous offspring. In addition to good luck and inborn physical strength, it appears they were particularly careful with their daily habits including diet. Since around the Fifth Century AD, Japanese rulers began building government-run pastures in many places to raise horses and cattle, from which meat and dairy products were regularly supplied. As this episode portrays, beef-eating was practiced since ancient times, the popularity of which was so high that the Tokugawa Shogunate often attempted to control its consumption with prohibitive orders. The Imperial Court also tried to discourage a meat diet as it did not want rice-growing peasants to consume meat. Samurai, the warrior-class people, however, regularly hunted for wild animals for their own consumption. Many samurai of the warring states generally kept manufacturing facilities for weapons and armor, and such facilities regularly produced fresh meat as byproducts. A meat diet was essential for the success of warlords of the era. The production of butter, on the other hand, was introduced through Kudara in Seventh Century AD, and butter was a popular gift to provincial governors. Milk and dairy products became popular in the 15th Century along with the introduction of Christianity to Japan, and in the 18th Century, Yoshimune, the Shogun of the time, created retail stores for milk. Milk never became popular, however, probably because it does not go very well with cooked rice, the ubiquitous staple food in Japan.