The over-seas traffic in slaves did not continue long after the date (1851) to which Barth referred, but slave-raiding by the Fula went on unchecked up to the moment of the British occupation of the country.
The question of the ethnic affinities of the Fula has given rise to an enormous amount of speculation, but the most reasonable theory is that they are a mixture of Berber and Negro.
They subdued the Fula and Arabs already settled in the district, and after being converted to Islam under Abdullah, their fourth king (about 1600), they extended their authority over a large number of tribes living to the south and east.
It has been erroneously stated that the Fula imposed Mahommedanism on the Hausa states.
He incurred the wrath of that king, who, angered at some act of defiance, ordered the massacre of every Fula in his dominions.
Negroid peoples predominate, but there are many pastoral Fula and Arabs.
The Mandingo, the Fula and the Susu are Mahommedans, though the Susu retain many of their ancient rites and beliefs - those associated with spirit worship and fetish, still the religion of the Baga and other tribes.
In 1897 there was a two-days' fight outside the walls of Bida between the forces of the emir of Nupe and those of the Royal Niger Company, ending in the defeat of the Fula army (mostly cavalry).
Like most conquering races the Fula are, however, not of uniform physique, in many districts approximating to the local type.
In the closing years of the century, Kano became the centre of resistance to British influence, and the emir, Alieu, was the most inveterate of Fula slave raiders.