1 Handbook of Number Edited by Paolo Acquaviva and Michael Daniel. Number marking in Karko and Nilo-Saharan Angelika Jakobi and Gerrit J. Dimmendaal 1 Overview of the number category in Karko and Nilo-Saharan Karko (kko, glottocode 1256, ISO 639-3) is a Nubian language spoken in the Nuba Mountains in southern Kordofan, Sudan. Nubian constitutes a well-defined subgroup within the Eastern Sudanic branch of the Nilo-Saharan phylum (see Figure 1). Eastern Sudanic constitutes the largest subgroup within Northeastern Nilo-Saharan, which further includes Maba, Fur plus Amdang, Kunama, Saharan, and Kuliak (Dimmendaal, Ahland, Jakobi, and Kutsch Lojenga, 2019); Northeastern Nilo-Saharan is one of the two primary branches of Nilo-Saharan, the other primary branch being Central Sudanic. 1 The areal distribution of Nilo-Saharan is shown in Map 1. 1 Disputed members of Nilo-Saharan, Songhay, and the Koman or B’aga group are not further considered here; see Dimmendaal, Ahland, Jakobi, and Kutsch Lojenga (2019) for further details.