Nauruans descended from Polynesian and Micronesian seafarers who believed in a female deity, Eijebong, and a spirit land, an island called Buitani. Two of the 12 original tribal groups became extinct in the 20th century. Angam Day, held on 26 October, celebrates the recovery of the Nauruan population after the two World Wars, which together reduced the indigenous population to fewer than 1500. The displacement of the indigenous culture by colonial and contemporary, western influences is significant. Few of the old customs have been preserved, but some forms of traditional music, arts and crafts, and fishing are still practiced.