This article records tradition as it has been passed down and reported. Its sources are not yet part of the atlas's verified catalogue.
Nile Green's global history of Sufism follows the tariqas as they actually spread, tracing documented lines of transmission between specific regions and languages rather than describing the phenomenon of the religious order as one uniform movement repeating itself unchanged from place to place. That approach matters for the study of religious orders generally, since an order founded in one region and period develops its own regional variations, branch lineages and local reputation as it spreads, and a serious history records those documented differences rather than assuming a founder's original teaching survived everywhere identically.
Establishing an order's own documented history means working from its own institutional records, its line of named successors where a tradition keeps one, and independent historical sources, rather than from the order's own later legendary or hagiographic accounts of its founding, which a careful study notes and treats separately from what can be independently documented.
Religious orders exist across many traditions, not only within Islam, though the tariqas that predominate among the atlas's present entries happen to be the tradition for which this kind of documented lineage study is unusually well developed, and an entry draws on that documented scholarship for an order's own institutional history rather than for its reserved teaching.