> I would say that "positive rights" is a fairly modern concept

Not really. “To no one will we sell, deny, or delay right or justice” in the Magna Carta has long been interpreted as much a positive right requiring the Crown to actually provide for justice rather than just a negative law to refrain from abusing it. There's also several clauses requiing royal justices to hold assizes in the counties and set procedures for hearing disputes which is a duty to maintain legal machinery. Heirs, widows, and wards were promised specific legal treatment, such as a widow’s immediate right to her marriage portion and inheritance, and limits on abuse by (non-state) guardians which are affirmative entitlements within feudal law.

Even Rome had the grain dole (the bread of “bread and circuses”).