The first non-Aboriginal people to visit and have long term contact with Aboriginal people in northern Australia were the Macassans from Sulawesi and other parts of Indonesia. They travelled to northern Australia every wet season, probably from the last quarter of the 17th century, in sailing boats called praus. They came to harvest trepang (sea cucumber), turtle shell, pearls and other prized items to trade in their homeland. Aboriginal people helped in harvesting and processing the trepang, and in collecting and exchanging the other goods.