History of Paella
The Moorish people of Al-Andalus often made casseroles of rice, fish and spices for family gatherings and religious feasts, thus establishing the custom of eating rice in Spain. This led to rice becoming a staple by the time the Catholics drove out the Muslims in the 15th century. Afterward, many cooks combined rice with vegetables, beans and dry cod, providing an acceptable meal for Lent. Fish always predominated with rice along Spain's eastern coast.
 Valencian paella
On special occasions, 18th century Valencians used paelleras to cook rice in the open air of their orchards near lake Albufera. The rata de marjal (marsh rat) was one of the main ingredients of early paellas, along with eel and garrafones (butter beans).
The rat-eating habits of the people of Valencia's rice-growing region were immortalized by Vicente Blasco Ibáñez in his novel Cañas y barro, a realist account about life among the fishermen peasants of the Albufera marshes in Valencia.
Living standards rose with the sociological changes of the late 19th century in Spain, giving rise to reunions and outings in the countryside. By then the original ingredients were replaced by rabbit, chicken, duck, seafood and sometimes snails. This dish became so popular that in 1840 a local Spanish newspaper first used the phrase paella valenciana to refer to the recipe rather than the pan.
The most widely used ingredient list of this era was as follows: short-grain white rice, butter beans, great northern beans, chicken, rabbit, snails (optional), duck (optional), runner beans, artichoke (a substitute for runner beans in the winter), tomatoes, fresh rosemary, salt, sweet paprika, saffron, garlic, olive oil and water. (Poorer Valencians, however, sometimes used nothing more than snails for meat.) It's these ingredients, and only these, that Valencians insist go into making modern Valencian paella.
 Seafood and mixed paella
Coastal residents substituted seafood for meat and beans, thereby inventing seafood paella. Later, Spaniards mixed seafood into the original Valencian recipe and mixed paella was born.
During the 20th century, paella's popularity spread past Spain's borders. As other cultures set out to make paella, the dish invariably acquired regional influences. Consequently, paella recipes went from being relatively simple to including a wide variety of seafood, meat, sausage, (the most popular being Spanish, chorizo)vegetables and many different seasonings. However, the most globally popular recipe is seafood paella.
In Spain, mixed paella is very popular. Some restaurants in Spain (and many in the United States) that serve this mixed version, refer to it as Valencian paella but Valencians insist only the original Valencian recipe can bear the name paella valenciana.
 International paella
Paella is now an international dish with recipes calling for ingredients very different from paella's original version.
Various international versions of paella are well known in Australia, Asia (especially the Philippines), Latin America (very popular in Mexico and Venezuela), the U.S., and West European countries such as Portugal, Germany, Sweden, Norway and Denmark