Eihei Dogen, also known as Dogen Zenji, lived from 1200 to 1253 in Japan. He was born in the province of Kii, in what is now known as the city of Kyoto. Dogen was raised in a noble family and received a traditional education in literature, poetry, and Confucianism.

At the age of 13, Dogen lost his mother, which deeply affected him and sparked his interest in Buddhism. He began studying Tendai Buddhism, one of the major schools of Buddhism in Japan at the time. However, he was not satisfied with the teachings and practices of Tendai and began searching for a deeper understanding of Buddhism.

In 1217, at the age of 18, Dogen traveled to China in search of a true teacher and a deeper understanding of Buddhism. He studied under the guidance of Master Rujing, a renowned Zen master of the Caodong lineage. Under Rujing's guidance, Dogen had a profound realization of the true nature of reality and attained enlightenment.

After returning to Japan in 1227, Dogen faced much criticism and opposition for his teachings, which were considered radical and unconventional at the time. He established his own monastery, Eiheiji, in 1244 and began teaching his unique interpretation of Zen Buddhism, which emphasized the importance of zazen (sitting meditation) and the integration of spiritual practice into daily life.

Dogen's teachings and writings, particularly his masterpiece "Shobogenzo" (Treasury of the True Dharma Eye), had a significant impact on the development of Zen Buddhism in Japan. He also emphasized the importance of monastic discipline and ethical conduct, which became the foundation of the Soto Zen tradition.

Eihei Dogen's legacy continues to influence Zen practitioners and scholars around the world. His teachings on the oneness of practice and enlightenment and the importance of living in the present moment have become central tenets of Zen Buddhism. Despite facing opposition and criticism during his lifetime, Dogen's teachings have stood the test of time and continue to inspire and guide many on the path to enlightenment.