Historically, even true monogamy (that is, monogamy not only on paper) would concentrate women on the upper end of the wealth/power scale, due to death by child

Historically, even true monogamy (that is, monogamy not only on paper) would concentrate women on the upper end of the wealth/power scale, due to death by childbirth. Most men would either have a sequence of wives, or none at all. Sufficiently well-organized places to not have robbery bands internally or raiding parties externally would, in absence of wars, often be big exporters of mercenaries.