The rectangular Kumma fortress, the L-shaped Semna fortress (on the opposite bank) and the smaller square fortress of Semna South were each investigated by the American archaeologist George Reisner in 1924 and 1928. Semna and Kumma also included the remains of temples, houses and cemeteries dating to the New Kingdom (1550–1069 BC), which would have been roughly contemporary with such lower Nubian towns as Amara West and Sesebisudla, when the second cataract region had become part of an Egyptian 'empire', rather than simply a frontier zone.