known today as Scandinavia.

As the Roman Empire flourished further south,

Scandinavians had small settlements, no central government, and no coinage.

Yet by the 11th century,

the Vikings had spread far from Scandinavia,

gaining control of trade routes throughout Europe,

conquering kingdoms as far as Africa,

and even building outposts in North America.

The secret to their success was their ships.

The formidable Viking longship

had its origins in the humble dugout canoe, or log boat.

For millennia,

the inhabitants of Scandinavia had used these canoes for transportation.

Dense forests and tall mountains made overland travel difficult,

but long coastlines and numerous rivers, lakes, and fjords

provided a viable alternative.

The first canoes were simply hollowed out logs rowed with paddles.

Over time, they added planks to the log boat base

using the clinker, or "lapstrake," technique,

meaning the planks overlapped

and were fastened to each other along their edges.

As the Roman Empire expanded north,

some Scandinavians served in their new neighbors' armies—

and brought home Roman maritime technology.

The Mediterranean cultures at the heart of the Roman Empire

had large warships that controlled the sea,

and cargo ships that transported goods along the waterways.

These ships were powered by sail and oars

and relied on a strong skeleton of internal timbers

fastened to the outer planks with copper, iron, and wood nails.

At first, Scandinavians incorporated this new technology

by replacing their loose paddles with anchored oars.

This change hugely improved the crew's efficiency,

but also required stronger ships.

So boat builders began to use iron nails for fasteners rather than sewing.

They abandoned the log boat base for a keel plank,

and the boats became higher and more seaworthy.

But these early ships retained the concept of the original log boat:

their strength depended on the outer shell of wood,

not internal frames and beams.

They were built as shells— thin-walled but strong,

and much lighter than the Roman ships.

Competing chieftains quickly refined the new ships to be even more efficient.

The lighter the boat, the more versatile it would be

and the less investment of resources it would require—

an essential advantage in a decentralized culture

without large supplies of people.

These ships still had no sails— sails were costly,

and for now the rowed ships could meet their needs.

That changed after the Western Roman Empire

collapsed in the 5th century.

Western Europe took a heavy economic blow,

leveling the playing field a bit for the Scandinavians.

As the region revived,

new and vigorous trade routes extended into and through Scandinavia.

The wealth that flowed along these routes

helped create a new, more prosperous and powerful class of Scandinavians,

whose members competed constantly with each other

over trade routes and territory.

By the 8th century, a sailing ship began to make sense:

it could go further, faster, in search of newly available plunder.

With the addition of sails,

the already light and speedy ships became nearly unbeatable.

The Viking ship was born.

Viking longships could soon carry as many as 100 Vikings to battle.

Fleets of them could land on open beaches,

penetrate deep into river systems, and be moved over land if need be.

When not at war,

the vessels were used to transport goods and make trade journeys.

There were smaller versions for fishing and local excursions,

and larger adaptations for open sea voyages

capable of carrying tens of tons of cargo.

Thanks to their inventiveness in the face of difficult terrain

and weak economies, the Vikings sailed west,

settled the North Atlantic and explored the North American coast

centuries before any other Europeans would set foot there.