Meanwhile, those lucky or in a position to play the system could amass a greater share of wealth.
The problem was, hierarchy and inequality weren't good for society's morale. When there are winners and losers, what reason do the losers have for sticking around to defend the winners from an invading army or nomad raiders?
Some might prefer to join the nomads or engage in some banditry instead.
Hence the practice of cancelling debts when a new monarch came to power. It was a practical way of maintaining the allegiance of commoners to the state and to the privileged hierarchy at its centre.
I tell this tale from the ancient world because there are parallels with today.
Within countries and between countries, we have a problem of inequality. Wealth disparities have only grown since the Covid pandemic hit.
In many countries, personal debt is worryingly high. Young people who don't have well-off parents are feeling aggrieved.
Inequality is stoking political tensions in every country, whether mature democracies or oligarchal states like Russia and China.
And it's contributing to military tensions between nations. Because rather than deal with the inequalities, one response is to try and unite a country by drumming up nationalism or even starting a war.
This is the world in which New Zealand might start looking at constitutional change. There will be different ideas about what we should do and at what speed.
But regardless of who our head of state is or whether one is even needed, shared allegiance to the state is undermined by inequality.
The Sumerian rulers understood this. That's why when one monarch died and a new one ascended the throne, they tried to heal society by cancelling debts.
The goal was to restore some equality (and political stability) which had been eroded in the previous years.
Skip forward a few millennia. On September 26, New Zealanders will get a one-off public holiday to mourn the death of Queen Elizabeth II. A surprising move in these supposedly modern times.
Yet I see a link to those attempts in the past to unite a citizenry after the death of a monarch. The Government has been smart (some might say calculating) in realising the opportunity.
I'm sure many would prefer their debts were cancelled, like in Sumerian times, but will take the paid holiday.
Though word is, if Matthew Hooton writing in the NZ Herald can be believed, Labour is considering cancelling student loan debt as its big election year promise.
In the United States, President Biden already has plans to cancel $10,000 worth of student debt for low-to-middle income borrowers.
At least some in ruling circles understand that you can't have a functional society when citizens are overburdened with debt and wealth inequalities are left to grow unchecked.
The vast stretch of time and geography between an ancient Middle Eastern civilisation ruled by kings and modern New Zealand seems, on the face of it, enormous. It's tempting to think we share nothing in common with those people and their attempts at state management.
And yet old problems persist, giving rise to the demand for old solutions.