For the regions west of Lake Chad the standard historical work is the Travels of Dr Heinrich Barth (5 vols., London, 1857-1858).
Bagirmi was made known to Europe by the travels of Dixon Denham (1823), Heinrich Barth (1852), who was imprisoned by the Bagirmese for some time, Gustav Nachtigal (1872), and P. Matteucci and A.
In 1851 Barth crossed the Benue at its junction with the Faro, but the region of its sources was first explored by Flegel (1882-1884), who traversed the whole southern basin of the river and reached Ngaundere.
It was visited by Hugh Clapperton, an English officer, in 1824, and in it Barth lived some time in 1851 and again in 1854.
Poggendorff immediately put himself in communication with the publisher, Barth of Leipzig, with the result that he was installed as editor of a scientific journal, Annalen der Physik and Cheinie, which was to be a continuation of Gilberts Annalen on a somewhat extended plan.
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.
Heinrich Barth made a prolonged stay in various Hausa cities at dates between 1851 and 1855.
In 1850 James Richardson, accompanied by Heinrich Barth and Adolf Overweg, reached the lake, also via Tripoli, and Overweg was the first European to navigate its waters (1851).
To Barth is due a great deal of our knowledge of the country.
Heinrich Barth (1851-1854) made known to Europe the course of the river from Timbuktu to Say.