there is a rather simple answer, but you don't see it much from either the identity politicians of the left, or the blind-to-oppression "post-left" scene; any way here it is:
The first moment of patriarchy in human societies marks the defining of certain bodies as being a thing from which value is extracted, and the social conditions and conditioning which facilitates such an extraction of value.
Sound familiar at all? Its also a description of the first moment that "classes" of people occur as a phenomenon in human relations; the those-who-work, and those-who-own. Between those who are managed and those who manage the others.
in the case of patriarchy, the subjugated class is marked as "women" which is to say not-male; and thus marked has foisted upon it the task of reproduction of humanity- what previously occurred by accident, or just as any other event in life, likely under the self-regulation of whatever herbology is known to the region, has been given a metaphysical quality of a duty, of work, of a job- but in its first instance its more like slavery. Naturally to humans, the class of women does not accept its subjugation to this commandment to be the factory of more humans, so the rullership of the male is put into place, as the controller of the reproductive class of women-- gender norms and heteronormativity flow from this, facilitating patriarchies control. Humans new born are entered into a system of social control directing some towards active enguagement, and others to mere use-value.
however, the first moment when bodies can be marked as those that are managed as value producers, is also the first moment of class- and it seems unthinkable to me that patriarchy and class were not co-evolutionary, as they flow from the same logic: Capital.