Original: The first European contact with chocolate came when Montezuma (then tlatoani of Tenochtitlan) introduced Hernán Cortés, a Spanish conquistador, to xocolatl in the 16th century.
Simplified: The first time Europeans saw chocolate was in the 16th century when Montezuma (who was ruler of the Aztec then) showed xocolatl to Hernán Cortés, a Spanish conquistador.