Following the defeat of General Gordon's troups in 1885, the Mahdist state (1885–1899) built important architectural monuments in Omdurman, the country's capital during this period. Today, the reconstructed tomb of Muhammad Ahmad, known as al-Mahdi, the former residence of his successor Abdallahi ibn Muhammad, now the Khalifa House Museum, as well as the Abdul Qayyum Gate and some remnants of the fortifications, known as "Al Tabia", bear witness to the Islamic tradition of Omdurman. Other characteristic buildings include mosques and graves of important religious leaders, such as Sheikh Hamed el Nil. Furthermore, "Souk Omdurman" is an important traditional market"."