Coffee likely originated in Ethiopia, where there are over 120 coffee species growing naturally. Ethiopia is also home to the “mother coffee tree” in the Kafa province. This coffee plant is much larger than average, and grows in the Mankira forest within the Kafa Biosphere Reserve. It functions as the center of the Arabica coffee plant universe, and can only be reached after a 9 hour hike.

The tree itself

The mother coffee tree stands about 6 meters tall, with a trunk roughly 20 centimeters thick, according to the German conservation group NABU, which works in the reserve. Most cultivated Arabica is pruned to a fraction of that height. The people of Mankira regard it as the origin of every Arabica coffee tree on earth. There is no scientific evidence for that claim, and NABU says so plainly. What is not in dispute is that it is one of the oldest coffee trees anywhere. Mankira sits about 12 kilometers south of Bonga, the old royal capital. The 9 hour hike is the wet season route. In the dry season, roughly October through March, a vehicle can get within a five minute walk of the tree.

The forest around it

UNESCO recognized the Kafa Biosphere Reserve in 2010. It covers 760,144 hectares, about 460 kilometers southwest of Addis Ababa, and holds more than half of Ethiopia’s remaining montane forest. It is part of the Eastern Afromontane Biodiversity Hotspot, one of the most biodiverse regions on the planet. The land climbs from about 500 meters to 3,300 meters. The middle band is Afromontane cloud forest, where fog hangs in the canopy most of the year and keeps the understory wet. The Gojeb River drains the reserve, and the surrounding hills are dotted with swamps, marshes, and peat bogs that are rare elsewhere in the country. The reserve’s managers count close to 5,000 wild varieties of Arabica in these forests.

Wild Arabica is a picky plant. It grows between 1,000 and 2,000 meters, and does best between 1,500 and 1,800. It wants roughly 1,600 to 1,800 millimeters of rain a year, an average temperature of 18 to 24 °C, and shade. Bonga sits at roughly 1,700 meters. The tree did not pick Kafa by accident. Kafa is the one place where all of those numbers line up at once, and have for a very long time.

What the ground is made of

About 30 million years ago, a plume of hot rock rose from deep in the mantle beneath what is now the Afar region. It broke through the crust and poured out the Ethiopia-Yemen flood basalts, one of the great volcanic events in the planet’s history. The lava covered roughly 600,000 square kilometers and totaled more than 350,000 cubic kilometers of rock. The same plume lifted the whole region upward, creating the Ethiopian Highlands. Without that lift, Kafa would be hot lowland like the country around it, and there would be no cloud forest.

In the southwest, the bedrock is volcanic rock from the late Eocene to the late Oligocene, capped with younger layers of volcanic ash. Warm temperatures and heavy rain have been breaking that basalt down ever since. The result is a soil type called Nitisol: deep, dark red, rich in iron and aluminum, with a clay structure that holds water without waterlogging the roots. Nitisols are the dominant soil of Ethiopia’s southwestern highlands and rank among the most productive soils in the tropics. A coffee tree with its roots in that soil rarely goes thirsty and rarely drowns.

The ground is still moving. Not long after the flood basalts, the continent began to split along the East African Rift. The rift runs down the center of Ethiopia and is still opening a few millimeters a year, with active volcanoes and regular earthquakes along its floor. Kafa sits on the western plateau, well away from the rift floor, on the older and more stable block. It gets the benefits of the uplift without the violence.

How Arabica came to be

Arabica is not an ordinary species. It is a natural hybrid of two other coffee plants: Coffea canephora, the lowland robusta of central and west Africa, and Coffea eugenioides, a small-fruited species of the east African highlands. At some point, one plant received a full set of chromosomes from each parent and kept both. That single event created Arabica. A 2024 study in Nature Genetics that sequenced the Arabica genome puts that event somewhere between 610,000 and one million years ago, in the forests of Ethiopia.

The same study found three population crashes in Arabica’s past. The oldest was about 610,000 years ago. Another stretch of very low numbers fell between 20,000 and 100,000 years ago, overlapping a long drought and cooler climate that hit the region roughly 40,000 to 70,000 years ago. The population grew again during the African Humid Period, about 6,000 to 15,000 years ago, when the highlands were wetter. Those crashes explain why Arabica has some of the lowest genetic diversity of any crop on earth, wild or cultivated. The wild populations that survive today come from the west side of the Rift Valley, which is where Kafa sits. The cultivated lines that reached the rest of the world came from the east side, near the strait that separates Ethiopia from Yemen.

A possible timeline

What follows is speculation. No one has found the first Arabica seedling, and no one will. But the geology and the genetics allow a rough story.

Thirty million years ago the plume lifts the plateau. Over the next twenty million years the highlands cool, rain falls on the new mountains, and montane forest spreads across the volcanic soil. Somewhere in that forest, canephora and eugenioides eventually meet. That may have happened during a wet period when lowland robusta crept upslope, or when the highland species pushed down into a valley. A single cross-pollination produces a seedling with a doubled set of chromosomes. Most such seedlings die. This one does not. That may have been about a million years ago.

Over the following ice ages, Africa dries out repeatedly. Each dry spell shrinks the forest, and Arabica shrinks with it, down to a few thousand plants in a handful of wet pockets. Kafa is a strong candidate for one of those pockets. It is high enough to stay cool, far enough west to catch the rains coming off the Congo basin, and sitting on soil that keeps water in the ground through a dry year. Each wet period lets the forest, and the coffee, spread out again. By the end of the African Humid Period, Arabica is a common understory shrub across the southwestern highlands. Then people show up, notice the red cherries, and the rest is written history. The mother tree, on this reading, is not the first Arabica. It is a descendant standing on the exact ground where its ancestors waited out the bad years.

The Kingdom of Kaffa

People have lived in these forests for as long as records exist. The Kingdom of Kaffa was founded around 1390 by the Minjo dynasty, which according to oral tradition ousted an earlier line of 32 kings. Bonga was the first capital, and later Anderaccha, though Bonga never lost its importance. The kings carried the title Tato. A monastery near Bonga dates to 1550, and the Tengola Mosque in the region goes back to the 13th century. Kaffa grew rich on trade with the northern Ethiopian empires. Its main exports were gold, ivory, civet musk, and slaves. Coffee was grown but in modest amounts. The historian Richard Pankhurst estimated the kingdom sold 50,000 to 60,000 kilograms a year in the 1880s.

The kingdom lasted five centuries. In 1897, Emperor Menelik II sent his armies south. The last Tato, Gaki Sherocho, the 19th ruler of the Minjo line, held out for eight months against Ras Wolde Giyorgis and the forces of King Abba Jifar II of neighboring Jimma. His soldiers fought with spears against rifles. He was captured on September 11, 1897, and died in captivity in 1919. A reconstruction of his palace stands today at an open-air museum in Bonga, built from the notes of the Austrian traveler Friedrich Julius Bieber, who visited the region in the years after the conquest.

The name and the legend

The famous story of coffee’s discovery belongs to Kaldi, an Ethiopian goatherd who supposedly noticed his goats dancing after eating red cherries from a bush. The story is a legend. It was not written down until 1671, and no one knows where in Ethiopia it is meant to have happened. Many people also assume the word “coffee” comes from “Kaffa.” That is a nice idea, but the more accepted path runs through the Arabic qahwa, the Turkish kahve, and the Italian caffè. What is well documented is that coffee crossed the Red Sea and was being cultivated in Yemen by the 15th century. From there it went to the world.

Every Arabica plant on every farm on earth traces back to a few seeds that left Ethiopia. The forest in Kafa is where the story starts, and the mother tree is the closest thing to a monument that story has.

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