20th century

This article records tradition as it has been passed down and reported. Its sources are not yet part of the atlas's verified catalogue.

A spread event entry in this atlas records one documented episode in which a religious tradition, practice or text reached a population or region it had not previously reached, together with its approximate date and the route or mechanism by which it arrived. Buddhism Reaches Sri Lanka and Buddhism Reaches China are examples already in this atlas: each names a specific, sourced episode of arrival rather than restating Buddhism's own founding, which belongs on Buddhism's own entry, not here.

A spread event entry records the mechanism of arrival wherever it is documented, since traditions have historically spread by more than one route: along established trade corridors, through missionary activity deliberately organized by a sending community, through conquest and the political sponsorship a new ruler sometimes extended to a tradition, and through migration, where a diaspora community carried its own tradition to a new home region rather than converting a new population to it. These mechanisms are not mutually exclusive within a single spread event; a tradition often reached a new region by trade contact well before any organized missionary effort followed.

Distinct spread events for one tradition are linked to each other chronologically wherever the record allows it, which lets a reader trace a tradition's documented reach across regions and centuries as a connected sequence rather than as isolated, unrelated facts. This is comparative history rather than an origin story: a spread event entry is deliberately silent on whether the tradition's own claims about itself are true, and records only what can be documented about when and how it reached a given place.

This article records tradition as it has been passed down and reported. Its sources are not yet part of the atlas's verified catalogue.

Several long-distance trade networks acted as corridors along which more than one tradition traveled, not just one. Along the Silk Road, Buddhism moved from South Asia into Central Asia and then into China, traveling alongside Zoroastrianism, Manichaeism, Nestorian Christianity and later Islam, each reaching the same string of oasis towns and garrison posts at different points, often arriving at a trading post or garrison town years or decades before the surrounding rural population encountered it at all. Studying this kind of spread means studying several traditions moving through the same physical space rather than any one tradition's isolated journey.

Historians working on trade-route spread rely on a mix of evidence that rarely survives as one continuous narrative for any single tradition: monastic cave inscriptions and manuscripts preserved by the dry conditions of desert sites, customs records and travelers' own accounts, and the archaeological record of temples, shrines and everyday objects left behind at oasis towns along the route. Because no one source type is complete on its own, these strands are routinely cross-checked against each other, and a claim resting on only one type of evidence is treated as more provisional than one corroborated across two or more.

Method in this field also distinguishes the date a tradition first reached a place from the date it became an established, self-sustaining community there, since the two are commonly separated by a long span and conflating them overstates how early a tradition genuinely took root. A single traveler's account or an isolated archaeological find can document first contact at a specific, early date, while the epigraphic or institutional record of an actual functioning community, monasteries, ordained clergy, a settled congregation, sometimes appears only generations later, and the field treats those as two different, separately documented facts rather than one.