Vietnamese Buddhism can be roughly divided into 4 periods:
1. From its beginning in Ancient Times to the 10th century A.D.,
2. Its Golden Age from the 11th century to the 14th century,
3. Its Decline in the 15th century and its Restoration in later centuries,
4. Contemporary Vietnamese Buddhism and its Activities in the present situation.
 
I. VIETNAMESE BUDDHISM FROM ANCIENT TIMES TO THE 1OTH CENTURY:
It is believed that among the three Buddhist centres of ancient China ( Lo Yang, Ring Ch’eng and Luy Lau ), Luy Lau centre in Giao Chau ( South China ) was then the first to be founded under the Han Dynasty ( around the early part of the first century AD ). Luy Lau, the capital of Giao Chau, which was then a Chinese vassal, was on the main trade route between India and China; therefore undoubtedly it became a favourable and prosperous resort for Indian pioneer missionaries to stay and preach the Buddha’s Teachings before continuing their journey to the North.

The Order of Giao Chau monks was founded before Buddhism spread to other places. From the evidence of historical records under the Latter Eastern Han Dynasty, we may conclude that Luy Lau was the first to adopt the new faith from Indian monks who gradually found their way to the North, i.e., South China and the Yangtse River Valley, and then to Lo Yang, the capital of China, where the two other Buddhist centres were successively founded. According to the documents recorded in THIEN UYEN TAP ANH ( an Anthology of the Most Talented Figures in Ch’an Park), our most ancient Buddhist literary collection, Master K’ang Seng Hui, a monk of Sogdiana origin was the first Buddhist Master at Luy Lau Centre. He was born in Giao Chau, where he was received into the Order of Monks afterwards. He became the most famous monk scholar who translated a large number of Buddhist Canonical books into Chinese ( Han characters ) and later he visited Nanking, where he built the first pagoda and preached the Dhamma. 

Besides Master K’ang Seng Hui, there were many famous Indian monk scholars such as Mahajivaka, Kalaruci ( Tche Kiang Liang ) and a Chinese scholar Mao Po ( Mui Tsu ), who immigrated to Giao Chau and studied Buddhism under Indian monks there. At that time, there were about 20 pagodas with at least 15 translations of Buddhist Text Books and 500 monks at Luy Lau centre. "The Buddha’s Sutta in 42 Sections" which appeared at Giao Chau in the 2nd century AD, is believed to be the first selection of Suttas translated into Chinese at Luy Lau.

Therefore, one of the characteristics of Vietnamese Buddhism in Ancient Times is that it had been introduced by Indian missionaries into Giao Chau long before it spread to China. The literary evidence in the above translation proved that in its very beginning, Vietnamese Buddhism adopted the fundamentals of Orthodox Buddhism from Indian monks and in later centuries with the development of Buddhism in China, it received another trend of Buddhist thought, the Mahayana doctrine, especially Chinese Ch’an Buddhism.

Another salient feature of Vietnamese Buddhism is that it has been closely connected with national life and Buddhist monks have made their active contribution to the construction and protection of their country. The best learned class of society, Vietnamese monks practised their religion side by side with common people and were on friendly terms with members of other religions such as Taoism, Confucianism. A large number of Ch’an Masters were great Confucianist scholars who, besides their religious duty, played an important part in social life. They might have made use of favourable conditions of Chinese Buddhism under the Sui ( in the 6th century AD ) and the T’ang dynasties ( in the 7th and 8th centuries ) in order to develop Vietnamese Buddhism and further a national movement for liberation from Chinese yoke.

The first period of DaiViet’s independence began with King Ly-Nam-De, who highly honoured Buddhism and used to consult Buddhist monks and follow their advice on religious and worldly affairs in protecting the young nation against foreign invasions. Finally came the glorious victory at Bach Dang River in 930, which opened a new page of DaiViet history.

II. THE PERIOD OF NATIONAL INDEPENDENCE FROM THE 11TH CENTURY TO THE 14TH CENTURY: THE GOLDEN AGE OF VIETNAMESE BUDDHISM:
The 10th century marked a new era of both the independence of DaiViet nation and the prosperity of Vietnamese Buddhism. Many Buddhist monks were engaged in politics under the Dinh ( 968-980 ), the Former Le ( 980-1009 ), the Ly ( 1010-1225 ) and the Tran ( 1225-1400 ) Dynasties. Some were appointed both "State Counsellors and National Teachers" such as Ch’an Masters Khuong Viet, Phap Thuan, Vien Chung and above all, Ch’an Master Van Hanh, who made his great contribution to the enthroning of King Ly-Thai-To, the founder of the Ly reign, and was later granted the title "Sangha President".

As a monk of great talent, he devoted himself to the teaching of the Dhamma and the construction of the kingdom; yet, he remained aloof from worldly life. His philosophical attitude was beautifully expressed in his serene and noble Utterance before his death: 
( Our personal existence is like a lightning flash that passes into nothingness,
All plants prosper in Spring and wither in Autumn,
Despite all the ups and downs of fortune, we fell no fear,
For these are mere dewdrops on the grasstips. )

The prosperity of Vietnamese Buddhism reached its height under the Ly and the Tran Dynasties during 4 centuries, King Ly Thai To and his successors were devout Buddhist supporters and patrons who officially recognized Buddhism as state religion and ruled righteously in accordance with the TEN DUTIES of a king ( Dasarajadhamma ). They showed their great compassion and tolerance towards their people, even criminals, prisoners and foreign enemies or rebels. By order of the Kings, thousands of pagodas and stupas were built all around the country, among which One-Pillar Pagoda (in Hanoi) was the most famous. Some of the kings resigned their power after a time of reigning, and became Ch’an Masters such as Ly Thai To, Ly Thanh Ton, Ly Anh Ton, Ly Cao Ton, Tran Thai Ton, and in particular, King Tran Nhan Ton, a great Buddhist scholar who, after his two victories over the Mongols (Yuang Meng), abdicated and became the founder of the Truc Lam (Bamboo Grove) at Mount Yen Tu. It was the first Vietnamese Ch’an Sect that had ever been founded and the king was consecrated as the first Patriarch of Truc Lam Ch’an sect of Viet Nam, the others being Vinitaruci (an Indian monk), Wu Yan T’ung (a Chinese), and Tsao T’ang (a Chinese). It was under his leadership that the 3 Ch’an sects (Vinitaruci, Wu Yan T’ung-Speechless Understanding, and Tsao T’ang-Hermitage) were unified into one Vietnamese Ch’an Sect.  

During the Golden Age, Vietnamese Buddhist thought, literature and architecture were best developed in poetry, in prose and in various works of arts. Above all, the achievement of engraving Buddhist scriptures which lasted 24 years (1295-1319) at Quynh Lam Pagoda under the auspices of King Tran Anh Tong was the most influential one. The great task was carried out by Master Phap Loa, the second Patriarch of the Truc Lam Ch’an Sect, alongside hundreds of monks and lay followers, making over 5000 engravings of Buddhist Scriptures including those composed by the Truc Lam Sect. Master Phap Loa made his best contribution to the growth of over 15.000 monks in more than 200 Truc Lam monasteries then. Next to Phap Loa was Huyen Quang, thus forming the Trinity of Truc Lam Patriarchs, the symbol of the Buddhist Golden Age. Master Huyen Quang, a great monk scholar and poet, led a secluded life at Mount Con Son, teaching the Dhamma, practising Ch’an meditation, and composing poems after 20 years of serving the Court.

What is essential of Truc Lam Ch’an Buddhism is that it lays the emphasis on the mental cultivation whatever condition one may live. It is a mind-oriented training for every Buddhist, whether he is a monk or a lay follower. This way of practising the Dhamma is best expressed in a hymn entitled "Cu Tran Lac Dao Phu" (Taking Delight in Religion While Dwelling in the World) composed by King Tran Nhan Ton, Truc Lam First Patriarch, who concluded the hymn with the following reputable verse:
 
( Let’s take delight in religion in whatever condition we may live,
Let’s eat when hungry and sleep when tired,
Within ourselves lies the gem, so let’s give up searching elsewhere,
When our mind is detached from the surroundings, there is no more question of concentration.)

Another interesting feature of Ly-Tran Buddhism is its trend of blending Buddhism with Taoism and Confucianism. This growing tendency of combining the 3 religions together in a harmonious way resulted in producing experts in the three branches of learning. Many of them were Ch’an Masters, kings and court mandarins who played a very active role as leaders in several struggles against the Sung’s army and later the Mongols’ invasions. In peace time as well as in war time, these Buddhists made their great effort to bring welfare and happiness to their nation. In the period of unprecedented prosperity of Vietnamese Buddhism, both Taoism and Confucianism were also well-developed and very popular with all social classes.

III. THE DECLINE OF BUDDHISM IN THE 15TH CENTURY AND ITS RESTORATION IN LATER CENTURIES:
By the end of the Tran Dynasty, as Confucianist scholars gained their monopoly at court, Buddhism gradually lost its influence especially after the invasion of the Ming in 1414, DaiViet became a Chinese vassal again, and the Ming rulers oppressed Vietnamese Buddhists by confiscating most of Buddhist text books in DaiViet, then sending them to Chin-Lang and destroying a large number of pagodas. Moreover, numerous talented monks were sent to China in exile. All that lay in the policy of assimilating the Vietnamese into the Chinese and spreading Confucianism as the only dominating doctrine while keeping Buddhism and Taoism under strict control.

After a ten-year fight against the Ming, finally came the victory won by Le Loi, the national hero who founded the Latter Le. But Buddhism was in unfavourable condition then: By King Le Thai To’s order, Buddhist monks had to pass an examination or they had to return to secular life. Confucianism had a great influence on the king and especially on the intellectuals of the time since it was the best way leading to power and glory at Court. What remained fortunate was that Buddhism had been so deeply rooted in all classes of people that they constantly kept their faith alive in hard times by building pagodas, temples and reprinting Buddhist Scriptures despite Confucianist scholars’ strong opposition and the kings’ exclusive order.

In the 16th century and during the Trinh-Nguyen Conflict lasting about 300 years, the Trinh and Nguyen Lords tried to restore Buddhism in order to win people’s heart. Many of them were devout Buddhists who decreed the building or renovating of lots of well-known pagodas or stupas such as Thien Mu Pagoda in Hue ( buy Lord Nguyen Hoang’s decree in 1601 ), Thien Tho ( Bao Giac) Pagoda, An Ton ( Tu Dam) Pagoda...
In the 17th century, a number of Chinese monks came to Vietnam founded such Ch’an sects as Lin Chi and T’sao Tung Sect. They were warmly received by the Trinh who, at the same time, encouraged the restoration of Truc Lam Ch’an sect. 

One of the brilliant torchlights of Vietnamese Buddhist Sangha in North Vietnam ( Dang Ngoai ) was Ch’an Master Chan Nguyen, who was conferred the title "Sangha President" by king Le Du Tong. The Master and his excellent disciples Nhu Hien, Nhu Trung made their great effort to restore the Truc Lam Ch’an Sect tradition and reprint numerous literary works composed by Truc Lam Patriarchs. Another outstanding figure was Ch’an Master Huong Hai, who preached the Dhamma at Nguyet Duong monastery to thousands of disciples. Some of them became very famous and were later appointed Sangha Presidents.

In the South ( Dang Trong ) , the Nguyen Lords heartily welcomed numerous Ch’an Masters from China. They founded the Lin Chi Sect and the T’sao Tung Sect and built pagodas in many provinces while the territory extended southwards. Besides, Vietnamese Ch’an Masters tried their best to restore Vietnamese Buddhism; among them, Ch’an Master Lieu Quan was considered the leader of the Buddhist restoration. He preached the Dhamma in many provinces and was highly esteemed by the Nguyen. He belonged to the Lin Chi Sect, but his teaching was coloured by Vietnamese way of thinking since he tried to remodel the religion imported from China, making it completely Vietnamese and lively in such aspects as rites and hymns or poems. His chief disciples continued to spread this way of teaching throughout the South and the influence of this Ch’an Sect could be found even in the Buddhist Restoration in the 20th century.
From the beginning of the French colonialists’ domination over Vietrnam, the condition of Buddhism was obviously worse. Under the Nguyen Dynasty, Buddhism got violent opposition from courtiers who were Confucianist scholars while it was neglected by most of the kings who were not zealous Buddhist supporters. In addition, as a time-honoured religion, Buddhism was confronted with many difficulties from the colonialist government.

IV. CONTEMPORARY VIETNAMESE BUDDHISM AND ITS ACTIVITIES AT HOME AND ABROAD. 

Under the influence of Chinese Buddhist Restoration in 1920, there was a movement for the Restoration of Vietnamese Buddhism headed by Master Khanh Hoa and many Buddhist associations were established in South VN, central VN and North VN from 1931 to 1934. The Buddhist Reformation received great approval from Buddhists especially the intellectuals in all over the country, but it was interrupted by World War II.
In 1948, the United VN Buddhist Association came into being and it resumed its activities in Ha Noi. Many Buddhist magazines and Vietnamese translations of Buddhist books were issued then. In Hue, the Most Venerable Elder Giac Tien and Doctor Le Dinh Tham, a lay Buddhist scholar, founded a Buddhist Institute at Truc Lam Pagoda, then "The Buddhist Association of An Nam" at Tu Quang Pagoda and two Buddhist schools for monks and nuns. It was Dr. Le Dinh Tham who made his best contribution to the Buddhist Restoration by disseminating the Buddha’s Teachings in Vietnamese, founding various Buddhist youth organisations and translating the Suramgama Sutra into Vietnamese. He was, in fact, the spirit of the Buddhist Restoration then.

In 1951, a National Buddhist Conference held in Hue aimed at unifying all Buddhist Associations and reorganising the Sangha’s activities. Besides, it approved the participation of Vietnamese Buddhists in the World Fellowship of Buddhists ( WFB ) founded in Colombo in 1950.

From 1954, after the division of VN into two regions by Geneva Agreement, Vietnamese Buddhists in the South suffered from the religious discrimination and restrictions imposed by the Diem Regime until the day when its oppression grew stronger and the non-violent Buddhist demonstrations broke out all over the countrry, the Bodhisattva Thich Quang Duc’s self-sacrifice (by burning himself alive for the cause of religion) followed by those of other Buddhist martyrs paved the way for the overthrow of the Diem Regime in 1963.
In 1975, after the Liberation Day of the South, there was a movement led by the Most Venerable Thich Tri Thu to unify all Vietnamese Buddhist sects and organisations and then the VN Buddhist Sangha was founded in 1981. The VN Buddhist Sangha headed by the Most Venerable Dhamma Patriarch Thich Duc Nhuan approved an action program for national co-operation and harmony among all Buddhist sects, disseminating the Dhamma at its best so as to make known its special features, establishing a system of monastic education and promoting friendship among world Buddhist organisations for peace on earth.

In 1981, the Institute of Higher Buddhist Studies was established in Hamoi, and in 1984, another one in Hochiminh City. Their purpose is to train a new generation of well-qualified monks and nuns so that they can effectively serve the VN Buddhist Sangha in various activities. The monk and nun students are instructed in both canonical and non-canonical subjects include the Doctrines of three main Buddhist schools: the Theravada (Orthodox Buddhism), the Sarvastivada (the Theory of the Pan-Realists) and the Mahayana (Developing Buddhism) Graduate students can continue their studies at home or abroad in order to become researchers at the VN Buddhist Research Institutre founded in 1989.

The VN Buddhist Research Institute as a new field of activiy of the VN Buddhist Sangha undertakes the important responsibility of elucidating the Buddha’s Teachings, emphasising creativeness in the Dhamma dissemination in accordance with the social and scientific progress of our time. Moreover, it tries its best to widen world Buddhist activities and promote exchanges of Vietnamese Buddhist culture with those of other countries.
The leadership of the VN Buddhist Research Institute consists of the Most Venerable Elder Thich Thien Sieu as Vice Rector in charge of the Department of Vietnamese Buddhism and the Venerable Dr. Thich Thien Chau (at Truc Lam Pagoda, France) as Vice Rector in charge of the Department of world Buddhism.

In addition, there are other Departments such as The Department of Buddhist Specialties, The Department of Monastic, Education, and above all, The Department of Translating and Publishing the Tipitaka (The Buddhist Canon) into Vietnamese. The great task of translating The Tipitaka from Pali, English and Chinese into Vietnamese, and publishing the Vietnamese Tipitaka has been under way since 1991. It will take about 2 decades to fulfil the assignment.

As far as world activities are concerned, the VN Buddhist Sangha’s (VBS) delegations attended the 6th and 7th ABCP general conferences and the Most Venerable Dr Thich Minh Chau was elected Vice President of the ABCP Leadership and President of the VN ABCP National centre. In 1984, the VBS delegation attended the Round-Table Conference in New Delhi and in particular, the VBS and the ABCP National Centre hosted the Conference of the ABCP Executive Council and the International Secretariat in Hanoi in 1985. In 1986, the International Year of Peace, two seminars on the theme "Buddhism and Peace" were held in Hanoi and HCM City. In recent years, many VBS delegations have attended religious seminars or conferences held in different countries such as India, Sri Lanka, Japan, Australia, Rome, France, Taiwan...

CONCLUSION
Throughout twenty centuries in the long history of VN, Vietnamese Buddhism has been closely linked with the survival of the nation, whether in its rise and fall. Since the early days of its introduction, the mind of Vietnamese Buddhists has been so well imbued with the Buddha‘s Teachings about love, tolerance and sympathetic understanding that Vietnamese Buddhism has been able to co-exist in peace with other religions for over 2000 years. On the one hand, generations of Vietnamese monks and nuns and lay followers, unknown or well-known, have somehow participated in making it a unique Vietnamese religion coloured with Vietnamese ways and customs. On the other hand, Vietnamese Buddhism has had a great influence on Vietnamese literature, art, music, architecture and Buddhism, so to speak, has become a part of Vietnamese life.