Citrus originated in the tropical and subtropical Asia. The citron was probably the first citrus known in Europe, probably the army of Alexander the Great introduced into the Mediterranean Sea basin, and quickly spread its cultivation. In ancient Rome it was used primarily as medicinal, and from the second century order food, Pliny records it in his Naturalis Historiæ . orange
The word derived ultimately narang Sanskrit, derived in turn from the Tamil nari, "fragrance", and transmitted by the Arabs and Persians. The Persian orange, grown widely in southern Europe after its introduction in Italy in the eleventh century, was bitter. The sweet orange was brought from India in the fifteenth century by Portuguese traders, quickly replaced the bitter, and now is the variety most commonly grown.
The lemon was unknown to the Greeks and Romans, being first mentioned in the book on agriculture Nabathae to the third or fourth century. Its culture was not developed in the West until after the Arab conquest of Spain, then spread throughout the coast Mediterranean.
Sources: Wikipedia
