Arabia Felix (lit. Fertile Arabia; also Ancient Greek: Eudaimon Arabia) was the Latin name previously used by geographers to describe the southern part of the Arabian Peninsula, and South Arabia. 
The term "Fertile Arabia" is a translation of the Latin "Arabia felix." Felix means "fecund, fertile" but also "happy, fortunate, blessed." Arabia Felix was one of three regions into which the Romans divided the Arabian peninsula: Arabia Deserta, Arabia Felix, and Arabia Petraea.
The southwestern corner of the peninsula, enjoying more rainfall, at that time was much greener than the rest of the peninsula and has long enjoyed more productive fields. The high peaks and slopes are capable of supporting significant vegetation and river beds called wadis help make other soil fertile.
Part of what led to Arabia Felix's wealth and importance to the ancient world was its near monopoly of the trade in cinnamon and spices, both its native products and imports from India and the Horn of Africa.
In the 1st century BC, the Arabian city of Eudaemon (usually identified with the port of Aden), in Arabia Felix, was a transshipping port in the Red Sea trade. It was described in the Periplus of the Erythraean Sea (probably 1st century AD) as if it had fallen on hard times. Of the auspiciously named port we read in the periplus that
- Eudaemon Arabia was once a full-fledged city, when vessels from India did not go to Egypt and those of Egypt did not dare sail to places further on, but came only this far.
- New Geographical Dictionary (Springfield, Mass., 1972), p. 63.
- Graf, D., R. Talbert, S. Gillies, T. Elliott, J. Becker. "Places: 746710 (Arabia Eudaemon)". Pleiades. Retrieved November 1, 2014.
- Harding, G Lankester (January–February 1965). "Inside Arabia Felix" (HTML). Saudi Aramco World. Houston, TX. 16 (1): 24–27. Retrieved 2009-07-06.