The Toucouleur Empire, though almost as large as that of the Sokoto Fulani to the east, is by no means so soundly based.
Whatever 'Umar's original motives may have been, his followers seem to have been as much concerned with amassing riches and power as with converting their subjects to Islam.
Numerous risings against Toucouleur authority by the conquered Bambara and Fulani continually shake the empire, and in 1864 'Umar himself is killed.
His son and successor, Ahmadu Seku, inherits a patrimony disturbed by inner conflicts and rival claims to power.
For the sake of internal order, in the 1880s he begins to disband his army and puts increasing reliance on the loyalty of subject peoples.
The policy fails; not only does Ahmadu fail to win new loyalties, but he loses the adherence of the Toucouleur themselves as they see their privileged position erode.
The French exploit the situation by constructing forts within Toucouleur territory and signing treaties of friendship with Toucouleur's neighbors.
After 1890, French troops sweep the empire, conquering Segu, Macina, and Timbuktu in turn.
Ahmadu succumbs to the French in 1893, and his former empire is soon firmly incorporated into French overseas territory.