Archaeologists have identified quarries used by the Yapese in a relatively small region of Palau, spanning the southern end of Babeldaob and the northern part of Koror. Some rai stones were found elsewhere in Palau, but the quarries, if any, had not been found as of 2006. Excavations were carried out at the quarries of Omis Cave on the island of Oreor, Chelechol ra Orrak and Upper Orrak on the island of Orrak, and Metuker ra Bisech on island with same name. The first two sites, caves/coves that open on the beach, appear to have been exploited before contact with Europeans, although the dates could not be determined. The other two sites are located uphill, at some distance from the beach. Quarrying at Metuker ra Bisech appears to have started only around 1700 CE, after the Yapese acquired iron tools. A large stone (3.5 m diameter, 20 cm thick) that apparently broke while being removed from the quarry at Metuker ra Bisech was abandoned on the spot.