It spoke of a fantastical realm,

containing the Tower of Babel and the Fountain of Youth—

all ruled over by the letter’s mysterious author: Prester John.

Today, we know that this extraordinary king never existed.

But the legend of this mythical kingdom and its powerful ruler

would impact the decisions of European leaders for the next 400 years.

Prester John’s myth would propel the age of exploration,

inspire intercontinental diplomacy, and indirectly begin a civil war.

When Prester John’s letter appeared, Europe was embroiled in the Crusades.

In this series of religious wars,

Europeans campaigned to seize what they regarded as the Christian Holy Land.

The Church vilified any faith outside of Christianity,

including that of the Jewish and Muslim communities populating the region.

Crusaders were eager to find Christian kingdoms to serve as allies in their war.

And they were particularly interested in rumors of a powerful Christian king

who had defeated an enormous Muslim army in the Far East.

In fact, it was a Mongol horde including converted Christian tribes

that had routed the army.

But news of this victory traveled unreliably.

Merchants and emissaries filled gaps in the story

with epic poems and Biblical fragments.

By the time the story reached Europe,

the Mongol horde had been replaced with a great Christian army,

commanded by a king who shared the Crusader’s vision

of marching on Jerusalem.

And when a letter allegedly written by this so-called “Prester John” appeared,

European rulers were thrilled.

While the letter’s actual author remains unknown,

its stereotypes about the East and alignment with European goals

indicate it was a Western forgery.

But despite the letter’s obvious origins as European propaganda,

the appeal of Prester John’s myth was too great for the Crusaders to ignore.

Before long,

European mapmakers were guessing the location of his mythical kingdom.

In the 13th and 14th centuries, European missionaries went East,

along the newly revived Silk Road.

They weren’t searching for the letter’s author,

who would have been over a century old; but rather, for his descendants.

The title of Prester John was briefly identified

with several Central Asian rulers,

but it soon became clear that the Mongols were largely non-Christian.

And as their Empire began to decline,

Europeans began pursuing alternate routes to the Far East,

and new clues to Prester John’s location.

At the same time these explorers went south,

Ethiopian pilgrims began traveling north.

In Rome, these visitors quickly attracted the interest

of European scholars and cartographers.

Since Ethiopia had been converted to Christianity in the 4th century,

the stories of their African homeland fit perfectly into Prester John’s legend.

Portuguese explorers scoured Africa for the kingdom,

until a mix of confusion and diplomacy finally turned myth into reality.

The Ethiopians graciously received their European guests,

who were eager to do business with the ruler

they believed to be Prester John.

Though the Ethiopians were initially confused by the Portuguese’s

unusual name for their Emperor,

they were savvy enough to recognize the diplomatic capital it afforded them.

The Ethiopian diplomats played the part of Prester John’s subjects,

and the Portuguese triumphantly announced an alliance with the fabled sovereign—

over 350 years after the European letter had begun the search.

But this long-awaited partnership was quickly tested.

A decade later, the Sultanate of Adal,

a regional power supported by the Ottoman Empire, invaded Ethiopia.

The Portuguese sent troops that helped Ethiopians win this conflict.

But by this time,

it was clear that Ethiopia was not the powerful ally Europe had hoped.

Worse still, the increasingly intolerant Roman Catholic Church

now deemed the Ethiopian sect of Christianity heretical.

Their subsequent attempts to convert the people

they once revered as ideal Christians

would eventually spark a civil war,

and in the 1630s, Ethiopia cut ties with Europe.

Over the next two centuries,

the legend of Prester John slowly faded into oblivion—

ending the reign of a king who made history despite having never existed.