A biogeographic realm that covers Europe, Asia north of the Himalaya foothills, northern Africa, and the northern and central parts of the Arabian Peninsula
Biogeographic realms are large spatial regions of the Earth’s land surface. Studying biogeographic realms leads to insight especially on biodiversity. It provides understanding on the extent of biodiversity and the factors that affect it. At present, there are about eight realms recognized by the World Wildlife Fund and they are divided according to their ecosystems sharing similar biological evolutionary history and distributional patterns of terrestrial organisms. The eight biogeographic realms are Nearctic realm, Palaearctic realm, Neotropical realm, Afrotropic realm, Indomalayan realm, Australasia realm, Oceanian realm, and Antarctic realm.
The Palaearctic realm (about 54.1 million square kilometres) is the largest biogeographic realm. It includes the bulk of Eurasian and North Africa. It also includes the northern and central parts of the Arabian Peninsula. There are several freshwater and terrestrial ecoregions in this realm such as the European Siberian; the Mediterranean Basin; the Sahara and Arabian Deserts; Western and Central Asian; and East Asia. The freshwater ecoregions of Palaearctic were deemed as the source of water for irrigation methods utilized by early civilizations.1
1 Palearctic realm. Retrieved from ://en.wikipedia.org/wiki/Palearctic-realm.