A few different important events took place during the 6th century A.D. One important religious movement was the development of Zen Buddhism. Zen developed during the 6th century from the school of Mahayana Buddhism. Just like Protestants separated from Roman Catholics due to political and doctrinal differences, so did Zen Buddhism split from Mahayana Buddhism. The schism developed between the Mahayana, meaning "Great Vehicle," and the Theravada, meaning "Small Vehicle." The two schools particularly differentiated in doctrinal beliefs concerning reincarnation. The Theravada believed that, like they saw the historical Buddha, once one reached Nirvana, the person left the reincarnation cycle. However, the Mahayana believed that the historical Buddha "after being persuaded to remain in life" made the personal choice to return to cycle through Samsara until all creatures simultaneously reached enlightenment ("Philosophy of Religion"). Zen Buddhism was specifically introduced by Bodhidharma, an Indian sage who lived between 470 and 543 A.D. and taught at a monastery in China. Also, similarly to what Martin Luther did for Christianity through the Protestant movement, Bodhidharma made the Buddhist religion less legalistic and less reliant on scriptures. He specifically taught not to depend on words and letters but rather to depend on man's mind and nature, for it is through one's nature that one attains Buddhahood or Nirvana.
A second important historical event that relates to religion can be seen in Emperor Justinian's decision to try and regain the Roman Empire because he believed he was preparing for Christ's second coming. In the 5th century, the Western Roman Empire fell and was divided up. However, the Eastern Roman Empire survived and was headed by Emperor Justinian I. The Eastern Roman Empire, also called the Byzantine Empire, consisted of Constantinople, which is now called Istanbul. In 532, attempting to secure his eastern frontier, he signed a peace treaty with Khosrau I of Persia agreeing to pay a large annual tribute to the Sassanids. He further laid sieges to recapture North Africa from the Vandals as well as to recapture Sicily. Ultimately, his military campaign was the most aggressive of any in the medieval period, and by the time of his death, he had expanded the Eastern Roman Empire to cover what borders most of the Mediterranean Sea ("The Byzantine State under Justinian I"). The purpose behind his conquests was purging all of the lands of paganism and unifying them under Christianity.