Before the development of the electric guitar and the use of synthetic materials, a guitar was defined as being an instrument having "a long, fretted neck, flat wooden soundboard, ribs, and a flat back, most often with incurved sides". Instruments similar to the guitar have been popular for at least 5,000 years. The six string classical guitar first appeared in Spain but was itself the product of a long and complex history of diverse influences. Like virtually all other stringed European instruments, the guitar ultimately traces back thousands of years, via the Near East, to a common ancient origin from instruments then known in central Asia and India. It is distantly related with contemporary instruments such as the tanbur, setar, and the Indian sitar. The oldest known iconographic representation of an instrument displaying all the essential features of a guitar being played is a 3,300 year old stone carving of a Hittite bard. The modern word, guitar, was adopted into English from Spanish guitarra (German Gitarre, French Guitare), loaned from the Andalusian Arabic qitara and Latin cithara, which in turn was derived from the earlier Greek word kithara, which is related to Old Persian sihtar.