The Romani, also spelled Romany or Rromani, colloquially known as the Roma, are an Indo-Aryan ethnic group who traditionally lived a nomadic, itinerant lifestyle. Linguistic and genetic evidence suggests that the Romani originated in the Indian subcontinent; in particular, the region of present-day Rajasthan. Their subsequent westward migration, possibly in waves, is now believed by historians to have occurred around 1000 CE. Their original name is from the Sanskrit word डोम (doma) and means a member of a Dalit caste of travelling musicians and dancers. The Romani population moved west into the Persian Ghaznavid Empire and later into the Byzantine Empire. The Roma arrived in Europe around the 13th to 14th century. Although they are dispersed, their most concentrated populations are located in Europe, especially central, eastern, and southern Europe, as well as western Asia.