The clan traces its founding in this area to Man Sai-ko, who settled near San Tin in the 14th century. Over the following centuries the Man family built their eight compact hamlet-like settlements — each one a lane or two of brick houses, tight and purposeful — and farmed the surrounding land. The wetlands that made the area sparsely populated were also what made it survivable; the brackish paddies provided food and a degree of natural defence. San Tin was never a grand clan seat in the manner of some New Territories villages, but it was enduring. Today a related community can be found at Tai Hang in Tai Po District, another area settled by members of the same Man lineage — the clan's footprint across the New Territories is wider than San Tin alone suggests.

San Tin's position near Lok Ma Chau has given it a peculiar modern significance. The Lok Ma Chau Control Point, served by the San Tin Public Transport Interchange, is the only 24-hour border crossing between Hong Kong and mainland China. Buses, minibuses, and taxis move through day and night, connecting Hong Kong travellers with their counterpart facility at Huanggang Port in Shenzhen. A separate spur line control point links to Futian Checkpoint across the border. For a place that spent most of its history as a quiet agricultural settlement, San Tin now sits astride one of the most intensively used land borders in the world — a transformation that happened within a single generation.

The barracks at San Tin carry a history that parallels Hong Kong's own. Before 1997, San Tin Barracks was known as Cassino Lines, a British military installation that housed various units over the decades — including Gurkha troops, the Nepalese soldiers who served in the British Army and formed one of the most distinctive presences in Hong Kong's garrison. When the handover transferred sovereignty to the People's Republic of China in 1997, the barracks passed to the People's Liberation Army Hong Kong Garrison, which occupies the site today. The Gurkha connection left a difficult legacy: reports have noted that Gurkha veterans have been denied access to approximately 200 graves that remain within the PLA-controlled compound.

The infrastructure that San Tin now supports would have been unimaginable to Man Sai-ko's descendants even a generation ago. San Tin Highway, completed between 1991 and 1993, runs northeast to southwest through the district as part of Route 9, connecting Fanling Highway in the northeast to Yuen Long Highway in the southwest near Kam Tin River. Slip roads from San Tin Interchange provide the critical link northward to the Lok Ma Chau border crossing, just two kilometres away. What was marsh and paddy has become one of Hong Kong's key logistical corridors — the physical expression of the territory's deep economic integration with the mainland that gathered speed in the 1990s and has not slowed since.

San Tin remains sparsely populated by Hong Kong standards. The marshlands that Man Sai-ko worked are mostly gone, but the low density they enforced has persisted. Eight hamlets, one district councillor, a handful of schools in the net that serves the area — the social geography still carries the marks of its agricultural origins. A proposed MTR station on the Northern Link has been discussed for years, with the Yuen Long District Council pressing for its construction. When or whether that station arrives will partly determine what San Tin becomes next. For now, the clan's homeland holds its particular balance: ancient lineage and 24-hour border traffic, brackish paddy names and PLA barracks, all compressed into a loosely defined patch of the New Territories.