In Southern Nevada, the Moapa Valley was dotted with the remains of ancient Anasazi dwellings. Many of these were built along the terraces of Anasazi Bench, which rises above the floodplain of the Muddy River. Eight sites along the Bench were located on land belonging to the Yamashita family. In 1989, the family granted permission for the University of Nevada, Las Vegas (UNLV) to survey and excavate these sites under the direction of Dr. Margaret Lyneis.

Named after the Yamashita family, the sites are numbered 1 through 8. Yamashita-2, 3, 4, and 5 are located on the upper terrace of Anasazi Bench, while Yamashita-6, 7 and 8 are located on the lower terrace closer to the floodplain. The development of a gravel quarry has destroyed Yamashita-1 and portions of Yamashita-2.

The area was surveyed and surface collections made at Yamashita-1 and Yamashita-4, 5, 6, 7 and 8. The Yamashita-8 site had been investigated prior to UNLV's efforts. The remains of adobe structures were discovered at Yamashita-2 and 3. These structures contained habitation rooms with some of the attached rooms forming an arc-shaped alignment. A more linear arrangement of attached storerooms was also present.

The architectural styles and ceramic types indicate Virgin Anasazi occupation of the sites during the Pueblo II period (A.D. 1000-1150). Evidence of later occupation by the Southern Paiute is also present The collections from the Yamashita sites are curated at the UNLV Department of Anthropology and Ethnic Studies, except for the Yamashita-8 collection.