Three small areas in the western Indian Ocean—the Persian Gulf, Red Sea and Gulf of Mannar—consistently dominated the world's pearl markets from antiquity until the advent of the cultured pearl industry in the 1920s. Most of these pearls came from the Ceylon Pearl Oyster, called bil-bil by Red Sea pearl fishermen. Remarkably, wild populations of this oyster have endured despite the many centuries of continual harvesting. Efforts are now underway to develop culturing techniques.