Buddhism Zen Buddhism is divided into two main schools: Rinzai (臨済宗) and Sōtō (曹洞宗), the former greatly favouring the use in meditation on the koan (公案, a meditative riddle or puzzle) as a device for spiritual break-through, and the latter (while certainly employing koans) focusing more on "shikantaza" or "just sitting". Zen Buddhism is primarily found in Japan, with some presence in South Korea and Vietnam. The scholars of Japanese Soto Zen tradition in recent times have critiqued the mainstream Japanese Buddhism for "dhatu-vada", that is assuming things have substantiality, a view they assert to be non-Buddhist and "out of tune
Zen Yasutani and the Sanbo Kyodan. This picture has been challenged, and complemented, since the 1970s by modern scientific research on Zen. Modern scientific research on the history of Zen discerns three main narratives concerning Zen, its history and its teachings: Traditional Zen Narrative (TZN), Buddhist Modernism (BM), Historical and Cultural Criticism (HCC). An external narrative is Nondualism, which claims Zen to be a token of a universal nondualist essence of religions. The history of Chán in China can be divided into several periods. Zen as we know it today is the result of a long history, with many changes and