The Kurds are an ethnic group who are indigenous to a region often referred to as Kurdistan, an area that includes adjacent parts of Iran, Iraq, Syria, and Turkey. Kurdish communities can also be found in Lebanon, Armenia, Azerbaijan (Kalbajar and Lachin, to the west of Nagorno Karabakh) and, in recent decades, some European countries and the United States (see Kurdish diaspora). Ethnically related to other Iranian peoples, they speak Kurdish, an Indo-European language of the Iranian branch. However, the Kurds' ethnic origins are uncertain.