Hyrcanian forests form a unique forested massif that stretches 850 km along the southern coast of the Caspian Sea. The history of these broad-leaved forests dates back 25 to 50 million years, when they covered most of this Northern Temperate region. These ancient forest areas retreated during the Quaternary glaciations and then expanded again as the climate became milder. Their floristic biodiversity is remarkable: 44% of the vascular plants known in Iran are found in the Hyrcanian region, which only covers 7% of the country. To date, 180 species of birds typical of broad-leaved temperate forests and 58 mammal species have been recorded, including the iconic Persian Leopard (Panthera pardus tulliana). © UNESCO