Black Man's Burden by Mack Reynolds

The young woman known as Izubahil was washing clothes in the Niger with the rest but slightly on the outskirts of the chattering group of women, which was fitting since she was both a comparative stranger and as yet unselected by any man to grace his household. Which, in a way, was passingly strange since she was comely enough. Clad as the rest with naught but a wrap of colored cloth about her hips, her face and figure were openly to be seen. Her complexion was not quite so dark as most. She came from up-river, so she said, the area of the Songhoi, but by the looks of her there was more than average Arab or Berber blood in her veins. Her lips and nose were thinner than those of her neighbors.

Yes, it was strange that no man had taken her, though it was said that in her shyness she repulsed any advances made by either the young men, or their wealthier elders who could afford more than one wife. She was a nothing-woman, really, come out of the desert alone, and without relatives to protect her interests, but still she repulsed the advances of those who would honor her with a place in their house, or tent.