WATERBERG, Namibia — In this faraway corner of southern Africa, scores of German soldiers lie in a military cemetery, their names, dates and details engraved on separate polished tombstones.

Easily missed is a single small plaque on the cemetery wall that gives a nod in German to the African “warriors” who died in the fighting as well. Nameless, they are among the tens of thousands of Africans killed in what historians have long considered — and what the German government is now close to recognizing — as the 20th century’s first genocide.

A century after losing its colonial possessions in Africa, Germany and its former colony, Namibia, are now engaged in intense negotiations to put an end to one of the ugliest chapters of Europe’s past in Africa.

During German rule in Namibia, called South-West Africa back then, colonial officers studying eugenics developed ideas on racial purity, and their forces tried to exterminate two rebellious ethnic groups, the Herero and Nama, some of them in concentration camps.