Smallpox is an infectious disease unique to humans, caused by either of two virus variants, Variola major and Variola minor. The disease is also known by the Latin  names Variola or Variola vera, which is a derivative of the Latin varius, meaning spotted, or varus, meaning "pimple". The term "smallpox" was first used in Europe in the 15th century to distinguish variola from the "great pox“,syphilis. This disease was the main fatal disease for native Americans in North and South America from the first European contacts through the 19th century. Historical records from Asia describe evidence of smallpox-like disease in medical writings from ancient China (1122 B.C.) and India (as early as 1500 B.C.  The earliest credible clinical evidence of smallpox is found in the Egyptian mummies of persons who died some 3000 years ago. It has been speculated that Egyptian traders brought smallpox to India during the 1st millennium BC, where it remained as an endemic human disease for at least 2000 years. Unmistakable descriptions of smallpox first appeared in the 4th century AD in China and the 7th century in India. Smallpox was likely introduced in China during the 1st century AD from the southwest, and in the 6th century was carried from China to Japan. In Japan, the epidemic of 735-737 is believed to have killed as much as one-third of the population. At least seven religious deities have been specifically dedicated to smallpox, such as the god Sopona in the Yoruba religion. In India, the Hindu goddess of smallpox, Sitala Mata, was worshiped in temples throughout the country. There are no credible descriptions of smallpox-like disease in the Americas before the westward exploration in the 15th century AD. In 1507 smallpox was introduced into the Caribbean island of Hispaniola and to the mainland in 1520, when Spanish settlers from Hispaniola arriving in Mexico brought smallpox with them. Smallpox devastated the native Amerindian population and was an important factor in the conquest of the Aztecs and the Incas by the Spaniards. Settlement of the east coast of North America in 1633 in Plymouth Massachusetts was also accompanied by devastating outbreaks of smallpox among Native American populations, and subsequently among the native-born colonists. Some estimates indicate case fatality rates of 80-90 % in Native American populations during smallpox epidemics.