Despite the Almoravid domination of Spain in the eleventh and twelfth centuries, there seems to be little evidence of contact during that time between Mauritania and Europe.

The inhospitable coastline of Mauritania continues to deter voyagers until the Portuguese begin their African explorations in the fifteenth century.

Lured by legends of vast wealth in interior kingdoms, the Portuguese establish a trading fort at Arguin, southeast of Cap Blanc (present-day Ras Nouadhibou), in 1455.

The king of Portugal also maintains a commercial agent at Ouadane in the Adrar in an attempt to divert gold traveling north by caravan.

Having only slight success in their quest for gold, the Portuguese quickly adapt to dealing in slaves.

In the mid-fifteenth century, as many as one thousand slaves per year are exported from Arguin to Europe and to the Portuguese sugar plantations on the island of São Tome in the Gulf of Guinea.

The islands of São Tomé and Príncipe, uninhabited before the arrival of the Portuguese sometime around 1470, are discovered by João de Santarém and Pêro Escobar.

Portuguese navigators explore the islands and decide that they will be good locations for bases to trade with the mainland.

The dates of discovery are sometimes given as December 21 (St Thomas's Day), 1471 for São Tomé, and ...

...January 17 (St. Anthony's Day), 1472 for Príncipe, though other sources give different nearby years.

Príncipe is initially named Santo Antão ("Saint Anthony").

The first Portuguese settlers on São Tomé and Príncipe, in search of land to grow sugar, arrive in 1493 to the uninhabited islands, which are right on the equator and wet enough to grow sugar in wild abundance.

The city of São Tomé is founded by Alvaro Caminha in 1493.

Subsequently, ...

…the north and center of the island of Príncipe will be made into plantations, most of them formed by Portuguese colonists using slave labor.

The cultivation of sugar on São Tomé and Príncipe is a labor-intensive process and the Portuguese begin to enslave large numbers of Africans from the mainland.

These slaves originate mainly from the Niger Delta and in Kongo.

Originally, the residents of São Tomé focuse on cultivating provisions for themselves, sustaining their slaves, and participating in the export of slaves.

A lack of value exists for the property on the island, as before the sugar boom, not much incentive remained to own land.

Foodstuffs often have to be imported, as cultivation on São Tomé is limited.

The low value of property is emphasized by the death of a São Toméan landowner, Álvaro Borges in November, 1504.

When Borges passes, his cleared land and domesticated animals are sold for merely 13,000 réis at a time when four slaves can be bought for 19,400 réis.

Although São Tomé, according to Valentim Fernandes around 1506, has bountiful sugarcane fields and even larger sugarcane than Madeira "from which they already produce molasses," the island is absent of the facilities needed for industrial levels of sugar production.

By 1515, São Tomé and Príncipe have become slave depots for the coastal slave trade centered at Elmina.

São Tomé only becomes economically noteworthy with the introduction of a land grant in 1515 of a water-powered sugar mill.

Just two years later in 1517, Portuguese documents highlight the importance of these sugar mills in the mass cultivation of sugar.

The documents state, "The fields are expanding and the sugar mills, too. At this time, only two sugar mills are here and another three are being built, counting the mill of the contractors, which is large. Similarly, the necessary conditions exist, such as streams and timber, to be able to build many more. And the [sugar] canes are the biggest I have ever seen in my life."

The expansion of sugar fields and production in São Tomé leads to the creation of plantations.

The creation of plantations results in an economic surge of sugar through slave labor.

Consequently, São Tomé's economy is based in sugar production and the slave trade.

By the mid-sixteenth century, the Portuguese settlers will have turned the islands into Africa's foremost exporter of sugar.

Slaves in São Tomé are bought from the Slave Coast of West Africa, the Niger Delta, the island Fernando Po, then later from the Kongo and Angola.

In the sixteenth century, the enslaved are imported from and exported to Portugal, Elmina, the Kingdom of Kongo, Angola, and the Spanish Americas.

In 1510, reportedly ten thousand to twelve thousand slaves had been imported by Portugal.

Then in 1516, São Tomé receives four thousand and seventy-to slaves with the purpose of re-exportation.

As a result, in 1519 the island becomes the center of the slave trade between Elmina and the Niger Delta, and will remain so up until 1540.

São Tomé is additionally harboring slave trade relationships intermittently with Angola and the Kingdom of Kongo throughout the early to mid sixteenth century.

Furthermore, in 1525 São Tomé had begun its slave trade relationship with the Spanish Americas.

Most of the slaves to the Spanish Americas go to the Caribbean and Brazil.

In the period between 1532 and 1536, every year São Tomé sends an average of three hundred and forty-two slaves to the Antilles.

Prior to 1580, the island will account for seventy-five percent of Brazil's imports, mainly exporting slaves.

The slave trade will remain a cornerstone of São Tomé's economy until the beginning of the seventeenth century.

Diogo Cão, shortly after making his initial contact with the Kongo Kingdom of northern Angola in 1483, had established links farther south with Ndongo—an African state less advanced than Kongo that is made up of Kimbundu-speaking people.

Their ruler, who is tributary to the manikongo, is called the ngola a kiluanje.

It is the first part of the title, its pronunciation changed to "Angola," by which the Portuguese refer  to the entire area.

Throughout most of the sixteenth century, Portugal's relations with Ndongo are overshadowed by its dealings with Kongo.

Some historians, citing the disruptions the Portuguese caused in Kongo society, believe that Ndongo benefited from the lack of Portuguese interest.

It is not until after the founding of Luanda in 1576 that Portugal's exploration into the area of present-day Angola rivals its trade and commerce in Kongo.

Furthermore, it is only in the early seventeenth century that the importance of the colony Portugal has established comes to exceed that of Kongo.

Although officially ignored by Lisbon, the Angolan colony is the center of disputes, usually concerning the slave trade, between local Portuguese traders and the Mbundu people, who inhabit Ndongo, but by mid-century, the favorable attention the ngola receives from Portuguese trade or missionary groups angers the manikongo, who in 1556 sends an army against the Ndongo Kingdom.

The forces of the ngola defeat the Kongo army, encouraging him to declare his independence from Kongo and appeal to Portugal for military support.

In 1560 Lisbon responds by sending an expedition to Angola, but in the interim the ngola who had requested Portuguese support had died, and his successor takes captive four members of the expedition.

After the hostage taking, Lisbon routinely employs military force in dealing with the Ndongo Kingdom.

This results in a major eastward migration of Mbundu people and the subsequent establishment of other kingdoms.

Following the founding of Luanda, Paulo Dias carries out a series of bloody military campaigns that contribute to Ndongo resentment of Europeans.

Dias founds several forts east of Luanda, but—indicative of Portugal's declining status as a world power—he is unable to gain firm control of the land around them.

Dias dies in 1579 without having conquered the Ndongo Kingdom.

Dias's successors make slow progress up the Cuanza River, meeting constant African resistance.

By 1604 they reach Cambambe, where they learn that the presumed silver mines do not exist.

The failure of the Portuguese to find mineral wealth changes their outlook on the Angolan colony.

Slave taking, which had been incidental to the quest for the mines, now becomes the major economic motivation for expansion and extension of Portuguese authority.

In search of slaves, the Portuguese push farther into Ndongo country, establishing a fort a short distance from Massangano, itself about one hundred and seventy-five kilometers east of Angola's Atlantic coast.

The consequent fighting with the Ndongo generates a stream of slaves who are shipped to the coast.

Following a period of Ndongo diplomatic initiatives toward Lisbon in the 1620s, relations degenerate into a state of war.

Spain's enemies subject the Portuguese colonies to attacks during the first half of the 1600s when Portugal, at the insistence of Spain, becomes involved in a succession of European religious and dynastic wars.

Holland, one of Spain's most potent enemies, raids and harasses the Portuguese territories in Angola.

The Dutch also begin pursuing alliances with Africans, including the king of Kongo and Nzinga of Matamba, who, angered by their treatment at the hands of the Portuguese, welcome the opportunity to deal with another European power.

When Portugal rebels against Spain in 1640, the kingdom hopes to establish good relations with the Dutch.

Instead, the Dutch see an opportunity to expand their own colonial holdings and in 1641 capture  Luanda and Benguela, forcing the Portuguese governor to flee with his fellow refugees inland to Massangano.

The Portuguese are unable to dislodge the Dutch from their coastal beachhead.

As the Dutch occupation cuts off the supply of slaves to Brazil, that colony's economy suffers.

In response, Brazilian colonists raise money and organize forces to launch an expedition aimed at unseating the Dutch from Angola.

In May 1648, the Dutch garrison in Luanda surrenders to the Brazilian detachment, and the Dutch eventually relinquish their other Angolan conquests.

According to some historians, after the retaking of Luanda, Angola becomes a de facto colony of Brazil, so driven is the South American colony's sugar-growing economy by its need for slaves.