The grouping of types eight, nine and one into a body or instinctive triad is often presented as ancient. It is not. The nine-pointed figure itself was introduced to Western audiences by G. I. Gurdjieff in the early twentieth century, who taught it as a symbol of process and did not attach personality types to its points. The types, and the triads that group them, come from Oscar Ichazo, who taught them at his Arica school from the late nineteen sixties, and from Claudio Naranjo, who took the material to groups in California in the early nineteen seventies. Everything specific about the body triad postdates that.
The scheme rests on the idea of three centres of intelligence, an instinctive one, an emotional one and a mental one, with three types clustered around each. The body triad is the instinctive cluster, and the emotion the literature associates with it is anger, appearing in three different forms across its three points: turned outward at eight, dulled or avoided at nine, turned inward as self-correction at one. That symmetry across all three triads, one emotion presented in three modes, is a construction of the modern enneagram literature rather than something inherited.
None of this makes the framework useless, and it should not be described as though its recency discredits it. It does mean the honest statement of its provenance is a named twentieth century lineage with living successors and continuing disagreement among them, not an anonymous ancient tradition.