Nowadays, many parts of the world are cultivated on terraces. These include Eastern Tigray (Ethiopia) and Southern Tunisia, where such terraces allow rain-fed agriculture without irrigation. The terraces of these two regions, however, have the particularity of being erected not on the slopes but in the valleys, which they cross perpendicularly to form flat cultivation areas and conserve water and soil on the plots. In Eastern Tigray, pre-Aksumite, Aksumite and post-Aksumite archaeological remains have been unearthed on the high points overlooking the terraced valleys. The cultural exchanges between these populations and the Sabaean populations of South Arabia, renowned for their hydro-agricultural works, are well documented today and lead to the hypothesis that terraces were ancient. Similarly, in Tunisia, the attested existence of hydro-agricultural developments from the Roman period in the region raises questions about the age and origin of the actually visible structures. A methodology combining geoarchaeology, geohistory and ethnogeomorphology allows apprehending these issues and estimating the period of installation of water and soil protection structures in the two studied areas, in a comparative perspective. Moreover, the contemporary evolution of these structures raises the question of their sustainability. In Eastern Tigray, agricultural terraces represent the main, if not the only means of subsistence for the populations. They are now subject to erosion. In Southern Tunisia, the recent rural exodus has exposed the structures to rapid evolution: destruction of low walls, loss of agricultural land by suffosion. Southern Tunisia thus allows a prospective reflection on the future of Tigray in the light of the ongoing rural exodus and questions the factors of regressive erosion in these two areas. More broadly, these two case studies can serve as analogues for reflection on other terraced areas, at different periods and in different regions.