Central Eurasia makes up the interior section of the Palearctic realm with four major subrealms -- Kazakh Steppes & Hemiboreal Forest, Caspian Sea & Central Asian Deserts, Tien Shan Mountains, and Persian Deserts & Forests -- containing nine bioregions in total. This area stretches from the Gulf of Oman to the Russian border and consists primarily of temperate grasslands and semi-desert. It encompasses most of Iran, Azerbaijan and the ‘stans,’ corresponding roughly to Central Asia. In the PersianDeserts subrealm there are two forested bioregions associated with the Zagros and Elburz mountain ranges in Iran along with expansive deserts that extend to western Pakistan. The largest subrealm is defined by the Caspian Sea to the west with desert and semi-desert ecoregions extending to the Tien Shan Mountains, which are particularly important for biodiversity containing over 2500 plant species and populations of the vulnerable and elusive snow leopard. In the north, the Kazakh Steppes subrealm stretches across the lower edge of Western Siberia and includes a narrow band of hemiboreal forests.