Ptolemy and Strabo, with the modern geographers, fix the Isthmus of Suez as the boundary of Asia and Africa. Dionysius, Mela, Pliny, Sallust, Hirtius, and Solinus, have preferred for that purpose the western branch of the Nile, or even the great Catabathmus, or descent, which last would assign to Asia, not only Egypt, but part of Libya.