 The first archeological expedition to the region was the 1989 "Three Rivers" expedition, which was carried out by a joint Mongolian–Japanese team with the support of the Yomiuri Shimbun newspaper.The team worked from 1989 to 1992 using ultrasound technology, which enabled them to find 1380 possible graves of Mongolian nobles.The idea of archaeological excavations, however, offends many Mongolians, who due to either superstition or respect for the leader believe that the Khan's resting place should be left undisturbed.