In the Congo valley the invaders settled in village and plain, absorbed such indigenous inhabitants as they found or drove them deeper into the forest, and immediately began to develop industry and political organization.  They became skilled agriculturists, raising in some localities a profusion of cereals, fruit, and vegetables such as manioc, maize, yams, sweet potatoes, ground nuts, sorghum, gourds, beans, peas, bananas, and plantains.  Everywhere they showed skill in mining and the welding of iron, copper, and other metals.  They made weapons, wire and ingots, cloth, and pottery, and a widespread system of trade arose.  Some tribes extracted rubber from the talamba root; others had remarkable breeds of fowl and cattle, and still others divided their people by crafts into farmers, smiths, boat builders, warriors, cabinet makers, armorers, and speakers.  Women here and there took part in public assemblies and were rulers in some cases.  Large towns were built, some of which required hours to traverse from end to end.

Many tribes developed intelligence of a high order.  Wissmann called the Ba Luba “a nation of thinkers.”  Bateman found them “thoroughly and unimpeachably honest, brave to foolhardiness, and faithful to each other and to their superiors.”  One of their kings, Calemba, “a really princely prince,” Bateman says would “amongst any people be a remarkable and indeed in many respects a magnificent man."[27]

These beginnings of human culture were, however, peculiarly vulnerable to invading hosts of later comers.  There were no natural protecting barriers like the narrow Nile valley or the Kong mountains or the forests below Lake Chad.  Once the pathways to the valley were open and for hundreds of years the newcomers kept arriving, especially from the welter of tribes south of the Sudan and west of the Nile, which rising culture beyond kept in unrest and turmoil.

Against these intruders there was but one defense, the State.  State building was thus forced on the Congo valley.  How early it started we cannot say, but when the Portuguese arrived in the fifteenth century, there had existed for centuries a large state among the Ba-Congo, with its capital at the city now known as San Salvador.

The Negro Mfumu, or emperor, was eventually induced to accept Christianity.  His sons and many young Negroes of high birth were taken to Portugal to be educated.  There several were raised to the Catholic priesthood and one became bishop; others distinguished themselves at the universities.  Thus suddenly there arose a Catholic kingdom south of the valley of the Congo, which lasted three centuries, but was partially overthrown by invading barbarians from the interior in the seventeenth century.  A king of Congo still reigns as pensioner of Portugal, and on the coast to-day are the remains of the kingdom in the civilized blacks and mulattoes, who are intelligent traders and boat builders.