Paul assisted Richthofen as guide and interpreter on exploratory journeys through 18 of China's provinces between 1868 and 1872[5] to report on the minerals, flora, fauna and peoples of the various regions.

While subsequently running a fur and wool trading business in Mongolia[6](1872–1881), Paul was called by viceroy Li Hongzhang to serve as Customs Inspector at the far western post of Jiuquan (also known as Suzhou[7]) on the border with Xinjiang (新疆).

After his Jiuquan assignment, Paul was called upon by agents of Leopold II of Belgium to use his understanding of Chinese language and protocol to negotiate revisions to a contract for the construction of the Beijing Hankou railway.

[8]Many explorers, including Richthofen's student, Sven Hedin, and famous Russian geologist Vladimir Obruchev have written about their unexpected encounters with the red-bearded Belgian Mandarin.

On the 100th anniversary of Paul's 1906 death, the farming town of Ottenburg/Huldenberg, where he spent his first 21 years as a foster child, a statue was erected in his honor by the regional historical society.