Travel in the East and diplomatic service
In 1892, Oppenheim travelled to Spain, the Maghreb and on to Cairo where he stayed for seven months, studying Arabic and Islam. Unusually, he moved out of a European-style hotel to live in a quarter inhabited by locals. In 1893–94, Oppenheim then travelled from Cairo through the Syrian desert and Mesopotamia to Basra. He passed through areas not visited by any European explorer before him and developed a keen interest in the Bedouins. Returning by way of India and Deutsch Ostafrika to Germany, in 1895 Max von Oppenheim wrote his two-volume travelogue Vom Mittelmeer zum Persischen Golf, which made him famous on publication in 1899/1900. T. E. Lawrence, whom Oppenheim later met at Carchemish in 1912, called Oppenheim's work "the best book on the area I know". In 1895, Oppenheim visited Constantinople and was received for an audience by Sultan Abdul Hamid II, discussing Panislamism.
Interested in politics and diplomacy, Oppenheim tried to join the diplomatic corps but he was first rejected by Herbert von Bismarck and then Auswärtiges Amt (Foreign Office) due to the Jewish background of his father. Using well-connected friends — including Paul Graf von Hatzfeldt — Oppenheim succeeded in being accepted as an attaché (which did not bestow diplomatic status) at the German General Consulate in Cairo. In June 1896, he arrived in Cairo which was to be his home for the next thirteen years. Not issued with any specific instructions, he made use of his freedom to engage in freelance activities, sending reports of his impressions to his superiors in Berlin (over the years totaling around 500). However, most of his messages were simply filed without comment, only rarely distributed more widely within the diplomatic service. Oppenheim was more successful in establishing a network of upper class acquaintances in Cairo, both European and local.
This activity and his views in support of the German government's colonial ambitions caused considerable mistrust among the British in Egypt, worried about German designs on the country (which had become a de facto protectorate in 1882), the Suez Canal and the lifeline to their possessions in India. The British press repeatedly agitated against him, even styling him a "master spy of the Kaiser". For example, when tensions were later heightened by the Aqaba border crisis,1906, British and French papers accused Oppenheim of acting in ways to incite pan-Islamic jihadi massacres of Europeans and of plotting with anti-French Algerian, and anti-Italian Tripolitan, rebels.
On one of several trips he made while stationed at Cairo, in 1899 Oppenheim travelled via Aleppo to Damascus and northern Mesopotamia on behalf of Deutsche Bank, working on establishing a route for the Baghdad Railway. On 19 November, he discovered the archaeological site of Tell Halaf, following up on tales told to him by local villagers of stone idols buried beneath the sand. Within three days, several significant pieces of statuary were uncovered, including the so-called "Sitting Goddess". A test pit uncovered the entrance to the "Western Palace". Since he had no legal permit to excavate, Oppenheim had the statues he found reburied and moved on. Deutsche Bank was not satisfied with his work on the railway and he was subsequently dismissed as an advisor. He continued to work in Cairo as a diplomat until 1910 when he was dismissed from the diplomatic service with the rank of Ministerresident on 1 November.