Ekayāna in the context of Mahāyāna sūtras

The Lotus Sūtra (Sanskrit: Saddharma Puṇḍarīka Sūtram, lit. 'Sūtra on the White Lotus of the True Dharma'; traditional Chinese: 法華經; simplified Chinese: 法华经; pinyin: Fǎhuá jīng; lit. 'Dharma Flower Sutra') is one of the most influential and venerated Buddhist Mahāyāna sūtras. It is the main scripture on which the Chinese Tiantai and its derivative schools--the Japanese Tendai and Nichiren, Korean Cheontae, and Vietnamese Thiên Thai schools of Buddhism--were established. It is also influential for other East Asian Buddhist schools, such as Chan and Zen. According to the British Buddhologist Paul Williams, "For many Buddhists in East Asia since early times, the Lotus Sūtra contains the final teaching of Shakyamuni Buddha—complete and sufficient for salvation." The American Buddhologist Donald S. Lopez Jr. writes that the Lotus Sūtra "is arguably the most famous of all Buddhist texts," presenting "a radical re-vision of both the Buddhist path and of the person of the Buddha."

Two central teachings of the Lotus Sūtra have been very influential for Mahāyāna Buddhism. The first is the doctrine of the One Vehicle, which says that all Buddhist paths and practices lead to Buddhahood and so they are all actually "skillful means" of reaching Buddhahood. The second is the idea that the lifespan of the Buddha is immeasurable, and that therefore, he did not really pass on into final Nirvana (he only appeared to do so as upāya), but is still active teaching the Dharma.

Tiantai or T'ien-t'ai (Chinese: 天台; pinyin: PRC Standard Mandarin:Tiāntāi) is an East Asian Buddhist school of Mahāyāna Buddhism that developed in 6th-century China. Drawing from earlier Mahāyāna sources such as Madhyamaka, founded by Nāgārjuna, who is traditionally regarded as the first patriarch of the school, Tiantai Buddhism emphasizes the "One Vehicle" (Ekayāna) doctrine derived from the influential Lotus Sūtra, as well as the philosophy of its fourth patriarch, Zhiyi (538–597 CE), the principal founder of the tradition. Brook Ziporyn, professor of ancient and medieval Chinese religion and philosophy, states that Tiantai Buddhism is "the earliest attempt at a thoroughgoing Sinitic reworking of the Indian Buddhist tradition." According to Paul Swanson, scholar of Buddhist studies, Tiantai Buddhism grew to become "one of the most influential Buddhist traditions in China and Japan."

Tiantai is sometimes also called "The Dharma Flower School" (天台法華宗), after its focus on the Lotus Sūtra, whose Chinese title translates to "Subtle Dharma Lotus Flower Sutra". During the Sui dynasty (581–618), the Tiantai school became one of the leading schools of Chinese Buddhism, with numerous large temples supported by emperors and wealthy patrons. The school's influence waned and was revived again in the Tang by figures like Zhanran, experiencing a second revival period during the Song dynasty. Chinese Tiantai remains a living tradition to this day, being particularly strong in Hong Kong and Zhejiang Province.