The Shwe Baw Gyun Lineage is part of an ancient and extensive Samatha tradition in Burma. Samatha literally means tranquility and concentration. In Burmese Buddhism, this particular Samatha lineage can be described as a mystical tradition. The term “mystical” is used because a better word has not been found to describe it.
I was told by my Guru that the Samatha tradition started at the time of Buddha and descended from his great disciples Sariputta and Mogallana. The only literature I’ve found, relating to how it came to Burma, was a book written by a Burmese Samatha lineage holder. In that book his Master said that Samatha was introduced to Burma by the Arahat Mahinda from Sri Lanka, via the Mon Kingdom of Thaton in the south of Burma.

The Samatha practice is unknown in the West, as the only tradition that was transported and popularized here is the Vipassana movement. However, among the lay Burmese, the Samatha tradition is the most ancient part of their spiritual culture and a more popular practice.

Vipassana became a significant part of the lay Burmese Buddhist life only a little more than a hundred years ago. It was popularized through the teachings of Masters Ledi Sayadaw and Thaton Sae Ta-wun Sayadaw and others. Prior to the modern era, Vipassana as a practice was, more or less, confined to the monastics. However, texts describing Vipassana have been preserved all through the centuries.

Samatha practices and scriptural studies — especially Abhidhamma (Buddhist psychology and metaphysics) — have been around for centuries. Most Burmese grow up learning to do Buddhanussati (contemplations on the virtues of the Buddha) through various mantras and Mettanussati (Loving Kindness meditation).

These devotional practices coupled with the Mangala Suta (the Blessings), the Metta Suta and other teachings, have had a great influence on the Burmese people, making them what they are today.

Going back to the lineage: it is also called the Inner Path as it has not been recorded or revealed in the Pali Canons. It can be said that it is only revealed to those who are born into or awakened to the lineage. It is handed down from generation to generation by Masters to disciples. Disciples are trained and groomed to hold the lineage and in time, they become Masters. They, in turn, train and groom their disciples to carry on the lineage. As far as my knowledge goes the lineage has not been broken for over a thousand years since Buddhism was introduced to Burma.

The Masters of the lineage are loving, highly respected figures. Most take Bodhisatta vows and strive to become a Buddha. Also, they accept the responsibility to be custodians of the Sasana, so the teachings could be passed on to the next generation … and preserved over time. Some of the Masters who do not vow to be Bodhisattas defer their last enlightenment (or Arahatship) until the next Maitreya Buddha’s time.
There is only one main Samatha tradition, but there are many groups within it. Each group or clan attracts individuals who are kammically associated with the lineage. Devotees are drawn to a specific Master of a particular clan.

Those who are to be groomed as future lineage holders are not identified at birth or at a young age. Their destiny may not be known to the parents or even themselves. They are born into and grow up in circumstances that are structured in a way that is necessary for their spiritual growth. They move through life by the force of their kamma and vipaka (fruition of kamma), and their particular parami (accrued merits and virtues) which they brought with them from the past. Individuals who are destined to be future Masters are largely invisible in society. They lead a normal life as a lay person or monk, and there is no external pressure on them. They can be men or women, though most of the Masters have been men.

The main practice for followers of the tradition are the Precepts. There are different Samatha practices — like Buddhanusati mantras and Metta meditation — which appeal to the masses. But, for individuals who are especially devoted, there are practices of varying degrees of intensity.

Asceticism is the rule and a way of life especially for those who are to be lineage holders. Diets vary from the withholding of land animals, to vegetarianism, to only consuming uncooked foods. Long periods of retreats at various holy sites, pilgrimages, and practising and studying under Masters are part of the tradition. Metta meditation is  the most important aspect of the practice. The ultimate goal is always Nibbana.
Masters guide their followers towards spiritual development, according to each individual’s ability and parami. They support the devotee’s unique nature in ways that are spiritually fulfilling and that lead to success. Followers on the Path are brought back to the lineage time and time again, in successive lives (wherever they are born), so that they may not go astray.
The lineage, its knowledge, and the way it functions, is revealed only to the lineage holders and faithful. It is a mystical Inner Path. This may be the reason why in Buddhist communities (like those in Burma) the Samatha tradition is widely misunderstood by the mainstream monastics and lay alike.