Burma first
Ledi Sayadaw's argument that lay people should practise insight meditation was taken up and systematised. Mahāsī Sayādaw developed a method of noting bodily and mental events that could be taught quickly, in a centre, to people who had never been monks, and Burmese centres trained thousands from the 1950s.
U Ba Khin, a lay teacher and a senior civil servant, taught a parallel method. His student S. N. Goenka moved to India in 1969 and began teaching ten day courses, free of charge, in a fixed format that has since been given in well over a hundred countries.
Thailand and the forest
The Thai forest tradition took a different route: not courses but apprenticeship, long residence in a monastery under a teacher. Ajahn Chah's Western students founded monasteries in Britain, Australia, New Zealand and elsewhere from the late 1970s, with full monastic training in English.
Buddhadāsa Bhikkhu, meanwhile, reinterpreted the teachings for a modern readership and argued that nibbāna is a matter of this life and not a distant realm.
Into the West
Joseph Goldstein, Jack Kornfield and Sharon Salzberg, all trained in Asia, founded the Insight Meditation Society in Massachusetts in 1975. What they taught, intensive retreat practice without monastic ordination, became the standard shape of Western Buddhist practice.
From there the practice passed into medicine and psychology, where it was stripped of its Buddhist framing. That was a deliberate choice by the people who did it, and it is the subject of the secular mindfulness story later in this timeline.
Why it matters
For many people outside Asia, meditation becomes the main doorway into Buddhism.
History and tradition
What historians can say
Well documented through the centres' own records and through Erik Braun's and others' scholarship on the Burmese origins. The important historical point is that mass lay insight meditation is recent: for most of Buddhist history, most lay people did not meditate, and did not expect to.