Dogen, the founder of Soto Zen Buddhism in Japan, was born in 1200 and is commonly known as Dogen Zenji or Dogen Kigen. His full name was Eihei Dogen Kigen, with Eihei being his family name and Dogen Kigen being his given name.

Eihei Dogen Kigen was born into a noble family in Kyoto, Japan. His father was a high-ranking official in the government, and Dogen was expected to follow in his footsteps. However, at the age of seven, Dogen's mother passed away, and this event had a profound impact on him. It sparked his interest in Buddhism and led him on a spiritual journey that would eventually lead to the founding of Soto Zen Buddhism in Japan.

Dogen studied various forms of Buddhism, including Tendai and Shingon, before traveling to China in search of a deeper understanding of the teachings. There, he studied under the guidance of the Chinese Zen master Rujing, who introduced him to the practice of zazen (sitting meditation).

After returning to Japan, Dogen established a monastery in the mountains of Echizen and dedicated himself to the practice of zazen. He also wrote extensively on Zen teachings, including his most famous work, the Shobogenzo, which is a collection of essays on Buddhist philosophy and practice.

Dogen's teachings emphasized the importance of zazen as the primary means of attaining enlightenment. He believed that through the practice of zazen, one could experience the true nature of reality and ultimately attain enlightenment.

In addition to his teachings on zazen, Dogen also emphasized the importance of living a simple and mindful life. He encouraged his followers to be fully present in every moment and to approach all activities, no matter how mundane, with a sense of mindfulness and reverence.

Dogen's teachings had a significant impact on the development of Zen Buddhism in Japan. His emphasis on zazen and mindfulness continues to be central to the practice of Soto Zen today.

In conclusion, the full name of Dogen, the founder of Soto Zen Buddhism in Japan, was Eihei Dogen Kigen. His teachings on zazen and mindfulness have had a lasting impact on the practice of Zen Buddhism and continue to inspire people around the world to this day.