Before telling you which rice is essential for making a good paella, I'm going to begin with a long preamble.
It's true! But I invite you to read it because it will help you grasp the spirit of paellas, and so avoid the mistakes that can spoil all your cooking results. Which would be a shame.
Cooking is like language: it is constantly evolving, and thankfully in ways that cannot be controlled. That is all its richness.
A simple example comes to mind: pizza. Once a hot starter on Italian tables, it was merely a leftover piece of bread dough rolled out, onto which a bit of leftover sauce was spread with the back of a tablespoon. Just a way of keeping the table happy while waiting for the main course.
Passing through France, it became generously topped and went back to Italy, amply garnished. Not an example to make us crow with national pride, but one to illustrate how culinary habits evolve and the constant changes that cooking undergoes.
And of course, in which you take part yourself, in effect, whenever you cook.
The same goes, not for THE paella, but for paellas. What is called "paella royale" in France does not exist in Spain. It is even better not to mention it. This name, modelled on couscous, is the fruit of the marketing brainstorming of the big supermarkets, and notably of Garbit.
A French company specialising in exotic products, it diversified its "Royal" Garbit couscous ("just like over there", as the advert said) with a paella, also called royale, like its couscous.
"ROYALE" PAELLA = ANDALUSIAN PAELLA
If we look at the different kinds of paella that exist in Spain (see table), our "paella royale" is none other than the Andalusian paella.
THE VERY FIRST PAELLA: CHICKEN, RABBIT...!
Historically, the very first one is the paella valenciana. Today it is codified in Spain, both for its ingredients and for the steps of its preparation. PDO, protected designation of origin, yes indeed!