Everyone leaves a legacy.

But a legacy can change over time as new generations re-examine old reputations.

From Wundery and Goalhanger Podcasts, I'm Afu Hirsch.

I'm Peter Frankepan, and in a brand new series we're exploring the lives of some of the biggest characters in history, from Napoleon to Picasso.

And asking, what does their past tell us about our present? This is legacy.

Follow now, wherever you get your podcasts. I'm John Bachelor visiting with Professor Peter Francopan who of Oxford University

his new book is The Earth Transformed and Untold History and we now go to a period that is striking in that

the Scandinavians now take a role as does climate because of the cooling of some temperatures before the

medieval war period and then suddenly the warming that was created the And again, Peter, I circled in my notes, low volcanism, correct? That is the explanation for why

this period is so stable.

That's one of the, that's one of, that's one of that's a prime reason but the natural cycles are also

important in that but also the ability to be successful so that those changes provide motivations and incentives and rewards to look out for new pastures.

Either because, for example, changes of wind direction or intensity or because of resource shortage, there are pressures and pools and pushes to look at new worlds.

And in fact, those expansions of the Vikings out into the North Atlantic towards Iceland, then Greenland and then Newfoundland

are mirrored at this about the same time, the same process by peoples in the southern oceans of the South Pacific, where there's a whole series of

colonizations of new areas and new islands that have never seen humans before.

And again, we can date some of this because of new scientific data and technologies, but in the case of the North Atlantic, some of the drivers towards because was to do with movements of shoals of fish further northwards into cooler waters as a result of the warming patterns.

Some to do with the fact that these new lands that were discovered offered new abilities, new goods

to trade, for example, walrus in large quantities that was very important

the walrus hides making high quality ropes or walrus tusks that were rival to elephant for ivory that was used in both religious and secular art.

And so suddenly sitting hitting a gold mine, so to speak, prompted high levels of colonization.

The challenge of course that the Vikings then ran into,

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