@0 it is entirely a colonial construct, force-fitting a non-hierarchical system into a hierarchy. Great psy-op too, in pushing it ... hard.

Most of the pre-colonial royal dynasties were from the supposedly lowest caste, with exactly one dynasty from the supposedly highest caste. The "lowest caste" was also the wealthiest, being the producer of all the spices and fine clothing that constituted almost ⅓ of global trade.