What is "zhiyi"

Zhiyi (; ) (538–597 CE) is traditionally listed as the fourth patriarch, but is generally considered the founder of the Tiantai tradition of Buddhism in China. His standard title was Śramaṇa Zhiyi (Ch. 沙門智顗), linking him to the broad tradition of Indian asceticism. Zhiyi is famous for being the first in the history of Chinese Buddhism to elaborate a complete, critical and systematic classification of the Buddhist teachings. He is also regarded as the first major figure to make a significant break from the Indian tradition, to form an indigenous Chinese system.