Greek dance (horos) is a very old tradition, being referred to by authors such as Plato, Aristotle, Plutarch and Lucian. There are different styles and interpretations from all of the islands and surrounding mainland areas. Each region formed its own choreography and style to fit in with their own ways. For example, island dances have more of a “watery” flow to them, while Pontic dancing closer to Black Sea, is very sharp. There are over 4000 traditional dances that come from all regions of Greece. There are also pan-Hellenic dances, which have been adopted throughout the Greek world. These include the syrtos, kalamatianos, hasapiko and sirtaki. Traditional Greek dancing has a primarily social function. It brings the community together at key points of the year, such as Easter, the grape harvest or patronal festivals; and at key points in the lives of individuals and families, such as weddings. For this reason, tradition frequently dictates a strict order in the arrangement of the dancers, for example, by age. Visitors tempted to join in a celebration should be careful not to violate these arrangements, in which the prestige of the individual villagers may be embodied. Greek dances are performed often in diaspora Greek communities, and among international folk dance groups.