Vietnamese Thiền, also known as Vietnamese Zen Buddhism, was founded by a monk named Venerable Thích Nhất Hạnh in the 20th century. Venerable Thích Nhất Hạnh was born in 1926 in central Vietnam and ordained as a monk at the age of 16. He received his formal education in Buddhism at Báo Quốc Temple in Huế, Vietnam.

After completing his studies, Venerable Thích Nhất Hạnh traveled to the United States in 1960 to further his education in comparative religion at Princeton University. During his time in the US, he also studied at Columbia University and became the first Vietnamese monk to earn a PhD in Buddhist Studies.

Venerable Thích Nhất Hạnh's teachings were heavily influenced by the Zen tradition, which he had studied extensively in Japan. Upon his return to Vietnam, he began to introduce Zen Buddhism to his home country, incorporating elements of Vietnamese culture and language into the practice.

In 1966, Venerable Thích Nhất Hạnh founded the School of Youth for Social Service (SYSS) in Vietnam, which focused on providing aid and social services to those affected by the Vietnam War. This organization, along with his teachings on engaged Buddhism, helped to bring attention to the suffering of the Vietnamese people and promote peace and non-violent activism.

However, due to his vocal opposition to the war and his efforts to promote peace, Venerable Thích Nhất Hạnh was exiled from Vietnam in 1966 and spent the next 39 years living in exile in France. During this time, he continued to spread the teachings of Vietnamese Thiền through his books, lectures, and retreats, gaining a following of students and practitioners around the world.

Venerable Thích Nhất Hạnh's teachings on mindfulness and engaged Buddhism have had a significant impact on the practice of Vietnamese Thiền. He emphasizes the importance of being present in the moment and using meditation as a means of cultivating inner peace and compassion, which can then be extended to others and the world around us.

Today, Vietnamese Thiền continues to thrive as a form of Buddhism that emphasizes simplicity, mindfulness, and social engagement. Venerable Thích Nhất Hạnh's teachings and legacy continue to inspire and guide practitioners around the world, making Vietnamese Thiền a significant and influential branch of Zen Buddhism.