This article records tradition as it has been passed down and reported. Its sources are not yet part of the atlas's verified catalogue.
Satsana Phi did not lose out when Theravada Buddhism became Laos's dominant and eventually state religion; it settled in beside it, and the two continue to run side by side in the religious life of most Lao communities. Wat Si Muang in Vientiane makes the arrangement visible in a single building: it is a working Buddhist temple, built in 1563, standing on the ruins of an even earlier Khmer Hindu shrine, and it also functions as the city's lak mueang, its guardian city pillar shrine, held to be watched over by the spirit of a local woman named Nang Si.
A Lao Buddhist visiting the temple is, in the same visit, paying respect to a phi, a spirit belonging to the older, indigenous layer of belief that predates the temple built around it. The same layering runs down to the household and village level: villagers who keep the Buddhist precepts also maintain the annual Liang Phi Ban offering to their village's guardian spirit, and mark life transitions such as marriage or a new job with a Baci ceremony calling the khwan, or personal spirits, back to the body, a rite with no equivalent in Buddhist doctrine at all.
Roughly thirty percent of the Lao population is counted as following Tai folk religion in its own right, but the deeper pattern is that far more Lao Buddhists practice both systems as one continuous religious life rather than choosing between them.