The Guinea Trade

Aguim – The First Portuguese Trading Center

While the Turks took control of Constantinople, the Portuguese began building a trading post on Aguim Island in the Bay of Aguim just south of Cape Branco on the west coast of today’s Mauritania. [The Dutch would change the spelling to today’s Aguin after they seized control in 1633.] It had been ten years since Nuno Tristão first visited the island in 1443. Henry figured out that the Portuguese were better off connecting with the Muslim Arab slave traders than chasing after natives to enslave them themselves.

The arrangement meant that the Portuguese needed to develop good relations with the Muslims in spite of their infidel beliefs. The Portuguese also needed to keep tight relations with the Genoese, Venetians, and Florentines because after the Muslims took control of Constantinople, the Italians were looking for new opportunities in which to invest their fortunes. Merchant bankers from Genoa, Venice, and Florence would make it rich in the Guinea trade. Ultimately, the new Guinea trade money partially funded Christopher Columbus’ expedition to Central America and John Cabot’s expedition to Newfoundland.

Cadamosto’s Journal

In 1454, a Venetian named Alvise da Ca’da Mosto [simplified to Cadamosto] joined Henry the Navigator’s team in Sagres. Cadamosto’s detailed journal about his travels provides us a colorful picture of what he and his fellow explorers experienced along the African coast.

Alvise and his brother Antonio Cadamosto grew up in Venice, where their father was an important merchant and owned a family home on the prestigious Grand Canal. But due to some unlucky lawsuits, the Signoria of Venice banished their father from the Republic. The brothers were left on their own to find work. They enlisted with the Venetian Northern Flotilla heading to Flanders.

On the way, foul winds and weather held the fleet up in Sagres. Prince Henry sent his secretary and a Venetian agent [the son of explorer Niccolò da Conti, whom we mentioned earlier] to board the Venetian ship for the purpose of selling Madeira sugar, dragon’s blood [the precious red fabric dye(1)] and other products. While on board, the secretary and the agent revealed to the Cadamostos how much shipmasters made when they worked for Prince Henry in the Guinea trade – six to seven times the profit shipmasters made elsewhere. With that, Alvise Cadamosto sold his interest in the Venetian expedition to his brother Antonio and joined Prince Henry at the Vila do Infante, where he was “entertained highly.”

In March of 1454, Alvise Cadamosto set sail in a caravel of fifty-five tons that Henry had outfitted. Vicente Dias(2), an experienced African trader, owned the ship and served as his pilot. Cadamosto had cut a very sweet deal with Henry. If he was successful, Henry would share the profits. If not successful, Henry would still bear the cost of expenses.

The caravel reached Pôrto Santo Island in the Madeiras in three days. Cadamosto reported a good anchorage but no harbor. The island produced wheat and barley; abounded in cattle, wild boars, and rabbits; and exported beeswax, Dragon’s Blood, and “the best honey in the world.” The coastal waters teamed with fish.

By the end of the month, Cadamosto reached Madeira Island. He wrote that it was as mountainous as Sicily, very fertile, and produced an immense amount of wheat. Sawmills in the streams supplied planking for shipbuilding and frame houses in Portugal. A cypress-like cedar grew in abundance, which was excellent for shipping since it did not need seasoning. The refined sugar was excellent, and the islanders produced more wine than they could drink. The animal life included wild peacocks, quail, wild boar, pigeons, and cattle. Many of the settlers in the four settlements were already wealthy.

Next stop was the Canary Islands, which were ruled by Castilian noblemen from Seville. On four of the islands, the Castilians had converted the native Guanche to Christianity. But on Tenerife, Palma, and Grand Canary, they had failed. The Guanche lived in caves and ran around naked except for an occasional goatskin cover. Cadamosto wrote that they were “the most nimble and dexterous people in the world. With a few blows they can shatter a shield [a description close to that of the gorillae people seen by Hanno the Navigator].” They were also very fashion conscious. “They esteemed the green, yellow, and red designs they painted on their skin as much as Europeans esteemed their fine clothing.”

Residents of the Christian islands had plenty of barley bread, meat, figs, and goat’s milk, but no wine or wheat. They exported goats leather and a die plant called orchil to Cádiz and Seville.

Cadamosto then sailed to Cape Branco, followed by Arguim Island, where he ran into treacherous shallow waters. He wrote, “One navigates only by day and with a lead in hand, and according to the state of the tide.”

Arguim was clearly a Portuguese colony. The houses were built in the European style, and so was the fort. A busy market flourished with goods carried in by the caravan routes. Everyone who traded there needed a license from Prince Henry. The Portuguese purchased from 800 to 1000 slaves a year from Berber and Arab traders, and then shipped them north. Henry had prohibited the Portuguese from raiding for slaves themselves. He was trying to maintain peace with the coastal people, so he could trade for gold.

The Portuguese brought in wheat, silver, silk handkerchiefs, and carpets, which they exchanged from the Arab traders for slaves and gold dust. The Arabs traded Barbary(3) horses from Morocco, which bought nine to fourteen slaves. Silk fabric came in from Granada. Gold dust came in by caravan from Timbuktu.

There was also a huge market for salt. The Arabs wanted salt “to keep men’s lips from putrefying on account of the great heat” in the Sahara. Caravans traveled inland to Melli [Mali] through lands so hot and arid that three out of four animals and many men died along the way.

Cadamosto described the trading procedure for salt: The Negroes, driven by Arab traders, carried the salt in large blocks on their heads to a “great waterway” [possibly the Niger River], where they deposited them on the shore. They then made themselves scarce a half-day journey away. From the other side of the waterway, the mysterious traders, who never allowed themselves to be seen, arrived in boats and placed piles of gold dust meant to match the value of the salt. The Arab traders returned to the shore. If they felt the payment was sufficient, they took the gold dust and left. If not, they made themselves scarce again so the mysterious traders would return with more gold dust. The parties continued back and forth until they made an agreement.

Cadamosto sailed from Arguim to the Senegal River, which he, as well as the Portuguese, called the Niger River, assuming it was the western end of the Nile. As you can see from the map below, the Niger River makes a curved path.

The Senegal River formed the boundary between the “lean tawny” Azenegueys [Tuaregs] and Berbers in the north and the tall black Africans in the south. Whereas the Azenegueys and Berbers were strict followers of Mohammad the Profit, and “always covered their mouths,” the Negroes were only nominal Muslims and did not cover their mouths “or any part of their head.” The Negroes lived in miserable reed huts and were ruled by a powerful Black King named Budomel.

The Black King was probably the leader of the Songhai Empire that dominated the green belt of the Senegal, Gambia, and Niger Rivers during the 1400s [the dark green or pink sections on the maps above]. Two bustling markets had formed in Timbuktu and Gao along the Niger River in today’s Mali. The markets were like the center of the wheel, and the trade routes led to them like spokes. Both cities were at the southern edge of the Sahara, the first stops salt traders reached in green lands after traveling through the scorching desert from the Mediterranean. From Gao and Timbuktu, gold and slaves traders traveled south to the Gulf of Guinea. Traders also traveled east and west via boats along the Niger River.

Alvise Cadamosto had heard of the Black King and brought Spanish horses in his caravel that he hoped the king would like. He found King Budomel many leagues south of the Senegal and stayed with him twenty-eight days. The king treated him as a leader of equal status, while the two casually discussed Islam, Christianity, and their views on the afterlife.

From there Cadamosto traveled inland looking for the gold markets. The inland people, not used to seeing Europeans, crowded around Cadamosto and his crew like the novelties they were. The Africans were particularly amazed at the European white skin. The most curious tried to rub the white off with wetted fingers as if it were paint.

The natives were equally amazed by the caravel. They thought the eyes on the figurehead were real, and that the eyes helped the ship find its way across the sea. They thought traveling across the sea was, in itself, a magical feat. They thought the crossbows and bombard were the work of the Evil One.

When Cadamosto reached the coast again, he met up with two more Portuguese caravels. One was commanded by a Genoese named Antoniotto Usodimane. The other was manned by two squires(4) of Prince Henry’s. Together the three ships sailed south to a very wide river, the Gambia. They ventured upstream until hostile Negroes, who believed the Europeans wanted to catch them to take them home to eat them, attacked with poison arrows.

After the inland trip, Cadamosto’s crew wanted to go home. He wrote “to avoid discussion, since they were pigheaded and obstinate men [we] turned back” for Portugal. The Gambia River is only 19 degrees north of the Equator. That night, Cadamosto and his crew saw six stars low over the sea, “clear, bright and large” in the shape of a cross. They had sighted the Southern Cross constellation, today known as Crux [from the Spanish word for cross, cruzar].

Cape Verde Islands

Alvise Cadamosto set out again in 1455 with the Genoese captain Antoniotto Usodimane. They were heading for the Guinea Coast in two caravels fitted out by Prince Henry when a storm hit and the Volta do Mar blew them west until they came upon the Cape Verde Islands. [It is not clear which one or ones.]

They stopped only long enough to store up on fish and catch some of the turtles that “had shells as big as a shield, and meat as tasty as veal.” Then they turned back to the River Gambia.

This time the explorers found a friendly tribe 20 leagues [about 69 miles] upriver and bartered for slaves, gold dust, apes, civet, civet cat skins, woven cotton cloth, Moroccan silk, and “European articles of little worth.” Cadamosto wrote about the enormous bats that zoomed overhead at night, and the hippopotami swimming in the rivers. The natives offered him some elephant meat to eat. Desiring “to eat something never before eaten by my own countrymen,” he tried it, but found it “tough and insipid.” Even so, he salted part of the trunk and a foot and took the morsels home to Henry.


In 1458, before the Portuguese could explore the Cape Verde Islands, they attacked Tangier again. This time they were more successful. [Too bad Fernando was already dead.] King Afonso V, accompanied by Prince Henry and King Afonso’s brother Fernando [Henry’s adopted heir](5) led a fleet of 280 sail with 2000 men. Once successful, Afonso passed the management of Tangier to Duarte de Meneses, who already supervised Ceuta.

Diogo Gomes’ Records

The records for this period in Portuguese exploration come from the experience of Diogo Gomes. Gomes was raised as a page in Prince Henry’s court before graduating to knight of the Order of Christ and explorer. He did not write the experiences down himself, but rather, in the 1480s, dictated them to Martin Behaim(6) of Nuremberg. [We mentioned Behaim earlier, and he will feature prominently in this book later. For now, remember that he was present in the Portuguese court in the 1480s.]

In 1458, Henry consigned Diogo Gomes to sail south in charge of three caravels. Gomes stopped by to visit the Black King on the Gambia River and learned more about the caravan routes between Cairo, Fez, Goa, Timbuktu, the Gold Coast, and the Slave Coast.(7) Gomes found out that gold came from “below the mountains,” an area the Portuguese would soon name Sierra Leão [Sierra Leone].

Castile Takes Possession of the Canary Islands

In 1459 the Castilians expelled the Portuguese from the Canaries, ending the tug of war that had been going on between the Castilians, French, and Portuguese since Henry tried to acquire the archipelago in 1448.

Last Expedition Under Prince Henry

In 1460, setting the last record met before Henry died, Pedro de Sintra coasted West Africa all the way to where it turns eastward, sighting the Sierra Leone mountains port-side. He came to a place with a forest of green trees he named Bosca de Santa Maria. Three small canoes rowed by, each with two or three “quite naked black men” carrying darts [probably poisoned]. Some of the men also carried knives, bows, and leather shields. Metal ornaments pierced the lower part of their noses. Some natives wore necklaces of what the Portuguese thought were human teeth.

The caravels were as much a novelty to the Negroes of Sierra Leon as Cadamosto had been to the natives of the African interior. One of the black men traveled back to Portugal with Pedro de Sintra and was able to communicate with a Negro woman slave at Henry’s Vila. After the Portuguese interrogated the man and gave him a fine set of clothes, they took him back to his country.

Exploring the Cape Verde Islands

While Pedro de Sintra broke records, Diogo Gomez and Antonio da Noli explored the Cape Verde Islands. They spent some time sailing from island to island, taking notes and staking their claims. According to the somewhat bitter account Diogo Gomes gave to Martin Behaim, on the way home, his caravel got caught in a storm and ended up in the Azores. By the time he got back on track and reached Lisbon, Antonio Da Noli had already arrived, presented himself to King Afonso V, and claimed to be the discoverer of the islands. King Afonso awarded Antonio Da Noli the captaincy [governorship] of Saõ Tiago Island [Portuguese for Saint James]. Gomes was not awarded anything.

Goodbye Henry

Prince Henry the Navigator died in Sagres on November 13, 1460, of “an illness.” His family buried him in the grand tomb for the House of Avis in the Monastery of Santa Maria. King João I began building the monastery in 1385 to thank the Virgin Mary [Santa Maria] for the Portuguese win at the Battle of Aljubarrota. The monastery was still under construction and would not be completed until about 1517 under King Manoel I.

Monastery of Santa Maria in Batalha.
[Referred to in today’s guidebooks as Mosteiro da Batalha.]   Photo by: Ingo Mehling, 2011.(8)

Henry is buried near all his brothers except Fernando in the Tomb of the Four Princes. Not far away are their parents João and Philippa. A cover-plate bears the inscriptions of the Order of Christ’s motto, “Por bem” [For the better] and the House of Lancaster’s motto, “Yl me plet” [I am pleased].

Tomb of King João I of Portugal and Philippa of Lancaster. Photo by: Nina Volare, 2007.(9) Tomb of the Four Princes. Photo by: José Luis Filpo Cabana, 2011.(10)

John dos Passos, in his book The Portugal Story: Three Centuries of Exploration and Discovery(11), [which we recommend highly for a more detailed account of the above], listed Henry’s accomplishments:

Henry died a debtor, for possibly as much as 30,000 gold duckets. For comparison, Lorenzo de Medici, who lived from 1449 to 1492, and was possibly the richest man in the world, was worth 200,000 gold duckets. Henry had passed all his profits from the Guinea trade to the Order of Christ, which in turn funded his explorations and fight against the infidels.

Henry’s nephew Fernando inherited: 1) the monopoly that the Pope had granted for exploration and trade, 2) the position as Grand Master of the Order of Christ, and 3) the title Duke of Viseu.

The Avis Dynasty, founded by Henry’s father King João I, will continue to rule Portugal until 1580, 120 more years.

Even though Prince Henry’s captains did not find a route under Africa to the Indies, they opened the secret door for the next generation of navigators who would. At the time of Henry’s death, printing had just been invented and the center of printing would soon pass from Germany to Venice. Presses in Lisbon were already printing books in Hebrew and Portuguese. The change caused by the invention of printing, which has been likened to the change in communication caused by the invention of the Internet, will help expand exploration more quickly than ever.(12)


  1. Dragons blood was a bright red resin made from a mixture of plant spices and materials. It had been in use since ancient times for varnish, medicine, incense, and dye.
  2. We do not know his relationship to Bartolomeu Dias.
  3. Barbary refers to the Berbers, who were the early “tawny-skinned” residents of Morocco before the Arabian Muslims migrated there. Most of the Berbers had converted to Islam by 1400.
  4. Squires were the lowest rank in the Knights Templar and Order of Christ. They were young men under the age of eighteen preparing to, one day, be knights.
  5. Reminder: both Afonso V and Fernando were Henry’s nephews. This Fernando was Henry’s brother Fernando died in Tangier].
  6. Martin Behaim was also known as Martinho da Boémia, Martin Bohemus, Martin Behaim von Schwarzbach, and in Latin as Martinus de Boemia.
  7. Map source:
  8. Photo by Ingo Mehling [CC BY-SA 3.0 (], via Wikimedia Commons. Image source:
  9. Photo by ho visto nina volare from Italy (PORTOGALLO2007) [CC BY-SA 2.0 (], via Wikimedia Commons. 2007 Image source:
  10. Photo by José Luis Filpo Cabana (Own work) [GFDL ( or CC BY-SA 4.0-3.0-2.5-2.0-1.0 (], via Wikimedia Commons. 2010 Image source url:
  11. Dos Passos, John. The Portugal Story: Three Centuries of Exploration and Discovery. Doubleday & Company, Inc., Garden City, New York, 1969
  12. At the same time, illuminated manuscripts flourished, and oil painting was developing in Flanders. Oil painting had to be invented before printing could be invented because the printing process relied on oil paint.

Next article: Crossing the Equator