Vietnamese Thiền, also known as Vietnamese Zen Buddhism, is a form of Mahayana Buddhism that originated in Vietnam. It is a blend of Chinese Chan Buddhism and indigenous Vietnamese beliefs, and has its own unique practices and teachings. Within Vietnamese Thiền, there are several branches or schools that have developed over time.

1. Linji (Vietnamese: Lâm Tế) School The Linji School, also known as the Rinzai School in Japan, is one of the oldest and most influential branches of Vietnamese Thiền. It was founded by Master Linji Yixuan, a Chinese monk who traveled to Vietnam in the 9th century. This school emphasizes the use of koans (paradoxical questions or statements) to help students break through their conceptual thinking and reach enlightenment.

2. Caodong (Vietnamese: Thảo Đường) School The Caodong School, also known as the Soto School in Japan, was founded by Master Dongshan Liangjie in the 9th century. This school focuses on the practice of silent sitting meditation, known as zazen, as a means to attain enlightenment. It also emphasizes the importance of mindfulness in daily activities.

3. Thien (Vietnamese: Thiền) School The Thien School is a Vietnamese branch of Chinese Chan Buddhism that emerged in the 11th century. It was founded by Master Thien Minh, who combined elements of both the Linji and Caodong schools. This school emphasizes the use of koans and silent sitting meditation, as well as the study of Buddhist scriptures and teachings.

4. Truc Lam (Vietnamese: Trúc Lâm) School The Truc Lam School was founded by Emperor Trần Nhân Tông in the 13th century as a way to promote Vietnamese Buddhism and culture. It combines elements of Thiền Buddhism with Confucianism and Taoism, and emphasizes the cultivation of moral virtues and the practice of meditation.

5. Lieu Quan (Vietnamese: Liễu Quán) School The Lieu Quan School was founded by Master Lieu Quan in the 18th century. It is known for its emphasis on the practice of mindfulness and the use of chanting and recitation of mantras as a means to achieve inner peace and enlightenment.

Each of these branches or schools of Vietnamese Thiền has its own unique practices and teachings, but they all share the common goal of helping individuals attain enlightenment and inner peace. Together, they have contributed to the development and spread of Vietnamese Zen Buddhism, making it an important part of the country's cultural and spiritual heritage.