Kurds are one of the largest and most important ethnic groups in the Middle East. There are between about 35 million and about 40 million Kurds. Most of the Kurdish population lives in Kurdistan. Kurdistan is the area where Kurds live. Today, it is a border country with lands in the east and southeast of Turkey, in the north-west of Iran, in the north of Iraq, and in the north-east of Syria. (Lands in Armenia and Azerbaijan also have small Kurdish populations.) After most of these borders came into existence after World War I, many Kurds went out of Kurdistan. They migrated to the large cities in the Middle East and to Western Europe. Since the Middle Ages, there have also been Kurdish communities in Cairo, Beirut, Damascus, and Aleppo. Since the Early Modern Period, there have also been Kurdish communities in Khorasan (north-eastern Iran and Afghanistan).