Oil wrestling (or Grease Wrestling) is the national sport of Turkey. It is a combat sport in which wrestlers douse themselves with olive oil. The wrestlers called "pehlivan" (meaning champion or hero) wear leather trousers which are hand-stitched and are known as kisbet made from water buffalo hide and most recently has been made of calfskin. Initially, the sport had no set duration but later in 1975, the duration was restricted to 40 minutes for baspehlivan & 30 minutes for the pehlivan category. The sport’s annual "Kırkpınar" tournament is taking place since 1362 in Edirne in Turkish Thrace and is the oldest continuously running competition in the world. Oil wrestling festivals are also held in northern Greece and West Thrace. In recent years, the sport is also becoming popular in other countries such as the Netherlands and Japan.