[hythloday]

It's the usage that originated with Lewis H. Morgan. Engels used it in "The Origin of the Family, Private Property and the State", which Wikipedia has a good summary of:

> Barbarism – the period during which man learns to breed domestic animals and to practice agriculture, and acquires methods of increasing the supply of natural products by human activity.

https://en.m.wikipedia.org/wiki/The_Origin_of_the_Family

[ue_]

For anyone wondering whether this work is worth reading, I must recommend The Origin of the Family, along with the other works of Marx and Engels. Engels has a wonderfully written The Principles of Communism which was the precursor to the Manifesto. They offer great insights into society.