Beginning in the early 1400s, European explorers carried European culture, including Christianity, to the farthest points on the globe. The primary motives for these voyages of discovery were financial profit and the creation of large empires. The church saw the voyages as an opportunity to bring Christianity to new converts in distant lands. Thus, priests and monks often accompanied explorers and conquerors as they sailed to America, Africa, and Asia.

Despite the acceptance of Christianity in Kongo and a few other African kingdoms, the popularity of the faith eventually declined in many of those states. Local peoples went back to their traditional beliefs and abandoned Christianity, which survived only among foreigners and their agents and slaves. By the 1800s, Christianity had vanished almost without a trace in many places.

The rest of Africa, however, remained a mystery to the outside world until medieval* travelers began exploring the continent. Arabs crossed the northern and western parts of Africa. The Chinese learned much about eastern Africa's coast along the Indian Ocean. Europeans spent hundreds of years charting the shores of Africa and then probing all of the continent's interior. Driven by trade, conquest, religion, science, or curiosity, generations of explorers gradually revealed Africa to the rest of the world.

The major European effort to explore Africa before 1500 took place at sea, not on land, and focused on Africa's western coast. In 1419 Prince Enrique of Portugal, known to later historians as Henry the Navigator, set up a research center on Portugal's south coast to gather information about Africa and to sponsor expeditions southward into waters unknown to European sailors. After the prince died in 1460, Portugal continued to send these explorers out to sea.

Traveling up the Nile to Berber, Baker spent a year wandering along the Atbara River and the Blue Nile, hunting and learning Arabic before returning to Khartoum, from which he and his wife launched an expedition up the White Nile in December 1862. Arriving at Gondokoro, the Bakers met the British explorers John Hanning Speke and James Augustus Grant, who had reached Lake Victoria and the Nile from the East African coast. In 1863-1864 Baker and his wife discovered and explored the eastern shore of Lake Albert, visited Kamrasi, the ruler of Bunyoro, and after many delays returned to London, where Baker wrote an extremely popular book about his explorations and the horrors of the Sudanese slave trade. In the spring of 1869 Baker was approached by Ismail, the khedive of Egypt, to lead an Egyptian expedition to the Upper Nile to extend Egyptian control to Lake Victoria, to claim the territory for Egypt, and to end the slave trade. Baker was consequently appointed governor general of Equatoria Province and sailed up the Nile with a large expedition of 1200 troops, the most expensive expedition to penetrate Africa.