Zen expected to become familiar with the classics of the Zen canon". A review of the early historical documents and literature of early Zen masters clearly reveals that they were well versed in numerous Mahāyāna Buddhist sūtras, including Madhyamaka. Especially the Lotus Sutra played a large role in the development of East Asian Buddhism, including Zen. Nevertheless, Zen is often pictured as anti-intellectual. This picture of Zen emerged during the Song Dynasty (960–1297), when Chán became the dominant form of Buddhism in China, and gained great popularity among the educated and literary classes of Chinese society. The use of koans, which
Dhyāna in Buddhism Zen, but makes Zen practice also vulnerable to misunderstanding and exploitation. B. Alan Wallace holds that modern Tibetan Buddhism lacks emphasis on achieving levels of concentration higher than access concentration. According to Wallace, one possible explanation for this situation is that virtually all Tibetan Buddhist meditators seek to become enlightened through the use of tantric practices. These require the presence of sense desire and passion in one's consciousness, but "jhāna" effectively inhibits these phenomena. While few Tibetan Buddhists, either inside or outside Tibet, devote themselves to the practice of concentration, Tibetan Buddhist literature does provide extensive instructions on it, and