Long before baby Jesus was born, people on the shores of the Bay of Bengal already enjoyed sugarcane. During his campaign in India, Alexander the Great marveled over this sweet plant, so different from honey which was commonly used these days. Around the 5th century, during the reign of the Imperial Guptas, crystallized sugar was discovered. Along trade routes and with the help of Buddhist monks, sugar soon spread to China and the Arab world. Arab businessmen first set up large scale plantations and refineries. In 1498, Portuguese navigator Vasco da Gama brought sugar from India to Lisbon which became the European sugar capital. By the 1800s, sugar was widely available to both upper and middle classes.
Nowadays, sugar is produced all over the world mainly from two plants: sugar beets and sugarcane. Sugarcane requires a sub- or tropical climate to grow well while sugar beets thrive in moderate climates. To produce raw sugar the juice of sugar cane is mixed with lime to achieve the desired ph balance and to help settle out impurities. The resulting liquid is reduced through evaporation. A centrifuge then separates the sugar crystals. A drying process produces granules.
To obtain white sugar, phosphoric acid and calcium hydroxide are added to sugar cane juice. These acids absorb or trap impurities. The resulting syrup is then filtered through a bed of activated carbon to remove molasses and then crystallized a number of times under vacuum. Commercial brown sugar is refined white sugar with molasses syrup mixed in, then dried again.
This description of sugar production comes from Michael Bloch's website http://www.greenlivingtips.com/articles/73/1/White-sugar-vs-raw-sugar.html. This might not be an independent source, but I checked with various websites sponsored by the sugar industry. The process seems to be fairly the same all over the world. Michael Bloch, the owner of the website, points out that commercial brown sugar is actually the worst sugar of all considering the impact on the environment. It requires all the processes of refined white sugar plus additional mixing and drying.