What is the X in X-mas?
1590s, from Spanish Inga (1520s), from Quechea Inca, literally "lord, king." Technically, only of the high Inca, but it was used widely for "man of royal blood."
A Native American people who built a notable civilization in western South America in the fifteenth and sixteenth centuries. The center of their empire was in present-day Peru. Francisco Pizarro of Spain conquered the Inca Empire.