Genetic evidence shows that rice (Oryza sativa) was first domesticated in the Pearl River delta of China, about 10,000 years ago. The two main varieties today are Chinese rice (Oryza japonica, which despite its name is Chinese and not Japanese) and Oryza indica, which is mainly grown in India.

From China, rice spread quickly to southeast Asia and India. The oldest evidence of rice from India dates to about 9,000 years. It was widespread by the time of the Indus Valley Civilization, where it was grown as a staple along with wheat.

There is a 3rd variety - Oryza glaberrima which is thought to have been independently domesticated in west Africa about 3500 years ago.

Rice spread to Europe and west Asia following Alexander’s conquests in the 4th century BC. The oldest evidence of rice in Europe or west Asia is from a grave in Susa (Iran) from the first century BC. From Iran it spread westwards into southern Europe, where it became fairly common by medieval times. Historically, all European rice was derived from indica, not japonica.

In Africa, Oryza glaberrima failed to spread very far. There was some cultivation of this rice in north Africa, but indica arrived sometime during the first millennium AD, and quickly replaced glaberrima. Probably the first exposure of Arab populations to rice was this indica that was grown in parts of north Africa, primarily the Nile delta. But it was scarce, and remained a small part of their cuisine. It was probably used in the same way as bulghur or couscous - part cooked and granulated for storage, boiled into a porridge or added to meat and vegetables. But wheat and barley dominated; rice was rare.

More extensive use of rice in Arab cuisine originates from the Mughal rulers of north India, who adapted many north Indian rice dishes and Persianized them, and spread them to central Asia and beyond. You can follow this spread etymologically, for example, the Indian pulao which is adapted into dozens of varieties of pilaf from Afghanistan to Turkey, all the way to paella in Spain. Muslim empires such as the Ottomans spread rice into Arab cuisines, but this is relatively recent.

It’s worth noting that although there are many popular rice dishes in the Arab world today, their per capita consumption of rice isn’t really that great. On average, people in Syria or Egypt or Lebanon eat about 12 kg per head per year, which has been steadily increasing as rice becomes cheaper and more widely available. It used to be only 5 kg per head per year as late as the 60’s. Compare that to predominantly rice-eating cultures like Japan, where the per capita consumption is over 100 kg, and you can see that while rice is common in Arab cuisine, it isn’t really their main staple. Rice is more common in some parts of the Islamic world like Iran and Afghanistan, but these places are closer to India. The Arabs are more at the periphery of rice consumption.

An interesting book in this regard is Rachel Laudan’s Cuisine and Empire. If you’re interested in scholarly papers on rice genetics, I can provide a few references if you want.