The delta region to the north is called Lower Egypt because of the direction and flow of the Nile River. The Nile flows from south to north, originating in the higher elevation areas of East Africa and flowing downwards into the Mediterranean Sea. Since rivers flow from higher to lower elevations, the northern Nile Delta region, where the river spreads out and empties into the sea, is at a lower elevation and hence called Lower Egypt. Conversely, the southern part of Egypt, which is upstream and higher in elevation, is called Upper Egypt. This naming system reflects the river's flow rather than geographic north-south orientation. In ancient times, Egyptians referred to Lower Egypt as the northern part and called it Tsakhet, meaning north. The Greeks and Romans later adopted the terms Lower Egypt (Aegyptus Inferior) and Upper Egypt based on this flow direction. Lower Egypt is also known as the Land of Papyrus due to the abundance of papyrus plants in the delta region. The Nile Delta itself formed as the river slowed and spread out into several branches depositing alluvial soil, which supported the development of agriculture and civilization in the area. In summary, Lower Egypt is the northern region near the Mediterranean where the Nile flows into the sea at low elevation, and Upper Egypt is the upstream higher elevation southwards region. The naming is based on the river's elevation and flow direction, not the cardinal directions on a map.