The scheme of seven centres arranged along the spine is widely known and is treated as a single traditional system. Its history is considerably more varied than that presentation suggests.
Early sources describe several different schemes
Texts from the relevant traditions give varying numbers of centres, with four, five, six, nine and other counts all appearing in different works.
Locations, names and associated qualities differ as well, and some influential texts place emphasis on centres that the popular model omits entirely.
What the sources share is the general idea of significant points along a central axis, not a fixed inventory of them.
Each scheme belongs to a practice
These descriptions appear within instructions for specific techniques, and the centres named are the ones that particular practice works with.
A system designed around one method has no reason to enumerate points that the method does not use, which accounts for much of the variation.
Treating the schemes as competing descriptions of one underlying anatomy therefore asks a question the texts were not answering.
Colour and sound associations came from several places
Correspondences between centres and colours, syllables, elements and deities appear in traditional sources, but the specific assignments differ between them.
The rainbow sequence familiar today aligns the centres with the visible spectrum, an ordering that reflects modern optics rather than any historical source.
That does not make the modern scheme useless as a practice framework, but it does make it a recent construction rather than an inherited one.
Translation and popularisation reshaped the model
The system reached wide audiences outside its home traditions through translations and through movements that combined it with other frameworks.
Those presentations selected one scheme, regularised it and connected it to psychological categories that the source texts do not use.
The result circulated widely and became the standard version, which is why most contemporary material shares a structure that older sources do not.
Claims about physiology need care
Attempts to identify the centres with particular glands or nerve plexuses are a modern development, made largely to reconcile the tradition with anatomy, and they are not supported as anatomical identifications.
The practices associated with the system involve breathing, posture, sustained concentration and visualisation, all of which have observable effects that can be studied on their own terms without settling the anatomical question at all.
Describing the framework accurately as a practice tradition, rather than as a hidden anatomy awaiting confirmation, keeps both the tradition and the evidence intact.