Egypt's "Black Land" (Kemet) refers to the fertile land along the banks of the Nile River, which was essential to ancient Egyptian agriculture and civilization. The term "Black Land" is contrasted with "Red Land" (Deshret), which refers to the desert areas surrounding it.
The fertility of the Black Land is largely attributed to the annual flooding of the Nile River. Each year, the river would overflow its banks, depositing nutrient-rich silt onto the surrounding fields. This natural irrigation and fertilization process created a conducive environment for agriculture, allowing the ancient Egyptians to grow crops such as wheat, barley, flax, and various fruits and vegetables.
In summary, Egypt's Black Land was primarily caused by the annual flooding of the Nile River, which brought fertile silt and made agriculture possible in the region.