The Tokugawa period, unlike the shogunates before it, was based on the strict class hierarchy originally established by Toyotomi Hideyoshi. The warrior-caste of samurai were at the top, followed by farmers, artisans, and traders.

Life in Tokugawa Japan was strictly hierarchical with the population divided among four distinct classes: samurai, farmers, craftspeople, and traders. Prior to the Tokugawa period there was some movement among these classes, but the Tokugawa shoguns, intent upon maintaining their power and privilege, restricted this movement. In particular they tried to protect the samurai, making upward mobility from the farming class to the samurai impossible. The shogun Hideyoshi decreed in 1586 that farmers must stay on their land. In 1587 he decreed that only samurai would be allowed to carry the long sword, which would later define them as a class. As economic conditions changed, the shoguns were less successful, however, in maintaining the rigid boundaries separating the other classes.

The proud warrior class of the samurai (meaning 'those who serve') grew from bands of mercenaries hired by feudal landowners in the 11th century to win them control of Honshu, Japan's main island. These mercenaries lived by the cult of the sword, worshipping athletic prowess and martial skills. They developed a fierce loyalty to their masters and a fearlessness that made them formidable adversaries. They fought in elaborate armour, weilding their most prized possession, a double-edged sabre with which they could cut a man in half. Later the spartan principles of Zen Buddhism, with it's love of nature, softened their fighting zeal. It became fashionable for them to live sparce and frugal lives during the Kamakura era (1192 to 1333), when the ruling warrior family Minamato moved their seat of power to the eastern city of Kamakura. Conficion thought, with its emphasis on honesty, also influenced the samurai.

By the 16th century these principles had become codified into bushido (meaning 'the way of the warrior). First loyalty remained to the samurai lord and to skill with the sword, but the warriors also became an Oriental version of the Christian knights, embracing duty, honour and nobility of spirit. In 1871 the last 400,000 samurai were pensioned off and became shizoku, Japanese gentry. Most were absorbed into the civil service and business management. Five years later it became illegal for anyone but the military to wear a sword. The virtues of the samurai were, however, kept as an ideal for the whole nation to follow, with the emperor as the supreme object of loyalty. This was the key that in times of crisis turned Japanese nationalism into a potent force.