Are the aggregates a pre-Buddhist concept? Do they appear in any of the Upanishads which pre-date Buddhism?
There is some correspondence :
"The Panchakoshas are listed as follows -
- Annamaya Kosha - The food sheath (body)
- Pranamaya Kosha - The vital energy or breath sheath
- Manomaya Kosha - The mind sheath
- Vijnanamaya Kosha - The intellect sheath
- Anandamaya Kosha - The bliss sheath"—Wikipedia
“Stephen Phillips suggests that Taittiriya Upanishad was likely one of the early Upanishads, composed in the 1st half of 1st millennium BCE, after Brihadaranyaka, Chandogya, and Isha, but before Aitareya, Kaushitaki, Kena, Katha, Manduka, Prasna, Svetasvatara and Maitri Upanishads, as well as before the earliest Buddhist Pali and Jaina canons.”—Wikipedia
This website quotes Sue Hamilton:
[…] the term khandha is distinctively Buddhist, not being found in the earlier Vedic literature except in the sense of ‘trunk”. Most frequently, the khandha are referred to by name without giving any explanation as to what the name means or implies; where descriptions are given, there are sometimes so brief that it is difficult definitively to ascertain the precise characteristics and functions of each one.