The seven-centre scheme is widely presented as the traditional Indian understanding of the body. Its textual history is narrower and more varied than that presentation suggests.
The systems belong to tantric ritual literature
Detailed descriptions of internal centres appear in tantric and hatha yoga texts composed over several centuries, well after the earliest Indian religious literature.
These texts describe centres as elements of visualisation practices, in which a practitioner constructs and works with an internal structure rather than reporting an anatomical discovery.
The vocabulary reflects that use. Centres are described with syllables, deities, petal counts and elements, all of which are components of a meditative procedure.
The number and placement vary between sources
Different texts and lineages describe four, five, six, nine or more centres, positioned differently and assigned different functions.
The scheme that became standard elsewhere derives largely from one particular text that reached European readers through an influential early translation.
That translation was widely read and repeatedly summarised, and the version it presented came to be treated as the tradition rather than as one branch of it.
The centres were tools rather than objects
In their original setting the centres serve practices of visualisation, breath work and mantra, undertaken within a lineage and usually under initiation.
Texts describe what a practitioner is to construct and experience, not a structure expected to be found by dissection or detected by instruments.
Reading these accounts as physiological claims imports a question the sources were not addressing, which is part of why attempts to verify or refute them tend to talk past the material.
Later layers were added elsewhere
Associations with a spectrum of colours, with endocrine glands and with a sequence of psychological themes largely developed outside India in the last century.
These additions drew on theosophical writing and later on popular psychology, and they arranged the centres into a developmental ladder that the older texts do not describe.
The result is a hybrid, coherent on its own terms and widely used, but distinct in origin from the tantric material it is attributed to.
The distinction matters for how claims are read
Historical description, contemplative practice and health claims are three separate registers, and they are frequently mixed in a single presentation.
The textual tradition can be studied historically, the practices can be undertaken within a lineage, and neither of those establishes physiological effects.
Practices of this kind are not a substitute for medical assessment, and anyone with a health concern needs a clinician regardless of what internal work they are undertaking.