This small island off the coast of Abu Dhabi is today the site of the country's principal oil refinery. In 1958 it was also the site of the first archaeological excavation in the then Trucial States, when several circular, collective tombs like those at Tomb A, Hili North, Tell Abraq, Mowaihat, Al Sufouh and Shimal were excavated. The excavation of a settlement on Umm al-Nar island confirmed the importance of the locale and for this reason the name 'Umm al-Nar culture' has been given to the period c. 2500-2000 BC in the UAE and Oman.