Sosan, also known as the Third Zen Patriarch, lived during the 7th century in China. He was born in the city of Caozhou, which is now known as Shandong Province. Sosan's given name was Chien-chih, and he was also known by his Buddhist name, Hui-neng.

Sosan was born into a poor family and was orphaned at a young age. He worked as a woodcutter until he was 24 years old, when he heard about the teachings of the Fifth Patriarch of Zen, Hung-jen. He traveled to the monastery where Hung-jen resided and became his disciple.

Under Hung-jen's guidance, Sosan practiced meditation and studied Buddhist texts. He quickly showed great understanding and insight into the teachings, and Hung-jen recognized him as his successor. However, Hung-jen's other disciples were jealous of Sosan's abilities and plotted to prevent him from becoming the Sixth Patriarch.

To avoid conflict, Hung-jen secretly transmitted the Dharma to Sosan and instructed him to leave the monastery and spread the teachings of Zen. Sosan traveled throughout China, teaching and spreading the teachings of Zen to people from all walks of life.

One of Sosan's most famous teachings is the Platform Sutra, which is a collection of his talks and teachings. In this text, he emphasizes the importance of understanding one's own mind and not relying on words or concepts. He also stresses the idea of "sudden enlightenment" rather than gradual enlightenment, which was a major departure from previous Zen teachings.

Sosan's teachings had a profound impact on the development of Zen Buddhism in China and later in other parts of Asia. He is considered one of the most influential Zen teachers and is revered as a patriarch in the Zen tradition.

In conclusion, Sosan lived during the 7th century in China and was born in the city of Caozhou, now known as Shandong Province. He was a woodcutter who became a disciple of the Fifth Patriarch of Zen, Hung-jen, and eventually succeeded him as the Third Zen Patriarch. Sosan's teachings, particularly the Platform Sutra, had a significant influence on the development of Zen Buddhism.