successors Mahu Bey Orfali and the first Governor-General, Ali Khurshid Pasha were more conciliatory, and Khurshid Bey agreed an amnesty for returning refugees who had fled to the Al-Atish border region with Ethiopia, as well as complete exemption from taxes for all shaykhs and religious leaders. Despite lack of early success in finding gold mines in Sudan, the Egyptians continued prospecting long after the initial conquest of the country. There was renewed interest in the Fazogli region in the 1830s, and Muhammad Ali sent European mineralogists there to investigate, eventually, despite being in his seventieth year, visiting the area himself in the winter of 1838–9. Only a small amount of alluvial gold was ever found, and in the end Fazogli was developed not as a mining centre, but as an Egyptian penal colony. Sudanese slave soldiers In the 1830s, as Muhammad Ali's military ambitions drew his attentions elsewhere, Egyptian manpower in Sudan was reduced and 'Ali Kurshid Pasha, Governor General of the Sudan 1826–38, had to increase the size of the locally recruited slave garrisons. He made periodic raids into the upper Blue Nile region and the Nuba Mountains, as well as down the White Nile, attacking the Dinka and Shilluk territories and bringing slaves back to Khartoum. Slave raiding was a demanding and not always profitable business however - in 1830 his assault on the Shilluk at Fashoda involved 2,000 soldiers but took only 200 slaves; in 1831-2 an expedition of 6,000 attacked Jabal Taka in the Nuba Mountains. The assault was not successful, and Khurshid lost 1,500 men. Rustum Bey, Governor of Kordofan under Khurshid, had rather more success, conducting slaving expeditions in the west. In January 1830, he led an expedition which took 1,400 captives. He selected 1,000 young males from among them and sent them to Egypt. in 1832, a similar expedition by Rustum yielded another 1,500 captives, who were recruited for the army. Khurshid's successor as Governor-General, Ahmed Pasha, found a more economical way of recruiting slaves. Instead of raiding to fill the gaps in his black regiments, he imposed a new tax whereby each taxable individual was obliged to buy and hand over one or more slaves. Governor-General Musa Pasha Hamdi (1862–65) combined both practices, requiring shaykhs and chieftains to supply him with specified numbers of slaves, and personally leading raids to capture others when this proved insufficient. Under the reign of the Khedive