In June 1768 he arrived at Alexandria, having resolved to endeavour to discover the source of the Nile, which he believed to rise in Ethiopia. At Cairo he gained the support of the Mamluk ruler, Ali Bey. After visiting Thebes, where he entered the tomb of Ramesses III, KV11, he crossed the desert to Kosseir, where he embarked in the dress of a Turkish sailor. After an extensive navigation of the Red Sea in a local vessel, he reached Jidda in May 1769, and after a stay in Arabia he recrossed the Red Sea and landed at Massawa, then nominally in possession of the Turks, but actually controlled by the local N'aib, on 19 September. He reached Gondar, then the capital of Ethiopia 14 February 1770, where he was well received by the nəgusä nägäst Tekle Haymanot II, by Ras Mikael Sehul, the real ruler of the country, by Wozoro Aster, wife of the Ras (whom Bruce calls "Esther"), and by the Ethiopians generally. His fine presence (he was 6-foot 4 inches high), his knowledge of Ge'ez, his excellence in sports, his courage, resource and self-esteem, all told in his favour among a people who were in general distrustful of all foreigners. He received court appointments as Gentleman of the Bedchamber and commander of the Koccob Horse, the Emperor's household cavalry. He stayed in Ethiopia for two years, gaining knowledge, copying books and collecting herbs that had special medical use, which he later presented as a gift to the French and Italian monarchs.