Christians wear crosses to remember the crucifixion of Jesus Christ (c. 6 B.C.E.–c. 30 C.E.) and because they believe that nothing unholy can stand in the presence of the cross. The cross as a Christian amulet dates back to the fourth century, when the Roman emperor Constantine (d. 337) adopted it as his symbol instead of the traditional Roman Eagle. That act symbolized the conversion of Rome to a Christian empire.
But amulets with crosses date back to Mesopotamia and Egypt, and served as a symbol long before associations of the cross with the crucifixion of Jesus Christ. Native Americans already had amulets with crosses by the time of first contact with Europeans. European adventurers, beginning with Christopher Columbus (1451–1506), assumed that Christians had arrived previously when they saw the crosses on Native Americans, but they were really viewing a people who invested belief in the power of a universal symbol. Crosses and circles are among the symbols and figures worn for protection and prosperity by humans since the earliest times. Such crosses often signified the four directions, the four forces (earth, water, air, and fire), and, when enclosed in a circle, the oneness of life.