Dogen, the founder of Soto Zen Buddhism in Japan, faced numerous challenges in spreading his teachings. His teachings emphasized the importance of meditation and the concept of "just sitting" as the key to enlightenment. However, his teachings were met with resistance and opposition from both the established Buddhist schools and the government.

One of the major challenges Dogen faced was the dominance of the established Tendai and Shingon schools of Buddhism in Japan. These schools had a strong influence on the government and the society, and they viewed Dogen's teachings as a threat to their authority. They saw his emphasis on meditation and the rejection of ritualistic practices as a challenge to their traditional teachings. As a result, they actively worked to suppress Dogen's teachings and prevent him from gaining followers.

In addition, Dogen's teachings were also met with skepticism and criticism from other Buddhist schools. Some criticized his interpretation of the teachings of the Buddha, while others saw his teachings as too radical and unconventional. This made it difficult for Dogen to gain acceptance and recognition from the wider Buddhist community.

Furthermore, Dogen's teachings also faced challenges from the government. During the Kamakura period, the government had a strong influence on religion and often interfered in the affairs of Buddhist schools. Dogen's teachings, which emphasized individual practice and the rejection of external authority, were seen as a threat to the government's control over religion. As a result, Dogen and his followers faced persecution and were often forced to go into hiding.

Despite these challenges, Dogen persevered and continued to spread his teachings. He established the first Soto Zen monastery in Japan, Eiheiji, and attracted a small but dedicated group of followers. He also wrote numerous texts and gave lectures to spread his teachings and gain recognition. Over time, his teachings gained acceptance and the Soto Zen school became one of the major Buddhist schools in Japan.

In conclusion, Dogen faced significant challenges in spreading his teachings, including resistance from established Buddhist schools, criticism from other Buddhist leaders, and persecution from the government. However, his determination and perseverance ultimately led to the establishment of Soto Zen as a major school of Buddhism in Japan.