From Tangier he made his way overland throughout the length of North Africa. He also travelled through Egypt, ascending the Nile to Wadi Halfa and crossing the desert to Berenice; While in Egypt he was attacked and wounded by robbers. Crossing the Sinai peninsula he traversed Palestine, Syria, Asia Minor, Turkey and Greece, everywhere examining the remains of antiquity; and returned to Berlin in 1847. For a time he was engaged there as Privatdozent, and in preparing for publication the narrative of his Wanderungen durch die Küstenländer des Mittelmeeres, which appeared in 1849.
At the instance of Bunsen and other scientists, Barth and Adolf Overweg, a Prussian astronomer, were appointed colleagues of James Richardson, an explorer of the Sahara who had been selected by the British government to open up commercial relations with the states of the central and western Sudan. The party left Tripoli early in 1850, but the deaths of Richardson (March 1851) and Overweg (September 1852) left Barth to carry on the mission alone. He returned to Europe in September 1855.
In addition to journeys across the Sahara, Barth traversed the country from Lake Chad and Bagirmi on the east to Timbuktu on the west and Caméroon on the south. He studied minutely the topography, history, civilizations and resources of the countries he visited. The story of his travels was published simultaneously in English and German, under the title ''Travels and Discoveries in North and Central Africa]] (1857?1858, 5 vols.).
Except a C.B., Barth himself received no recognition of his services from the British government. He returned to Germany, where he prepared a collection of Central African vocabularies (Gotha, 1862?1866). In 1858 he undertook another journey in Asia Minor, and in 1862 visited Turkey in Europe. In the following year he was appointed professor of geography at Berlin University and president of the Geographical Society. He died at Berlin on the November 25, 1865.