People discovered a long time ago that if grapes were left out to dry in the sun, they became raisins, the question was finding the varieties which would give best results.
Apparently the first people to do any grape selecting were the Phoenicians and Armenians. In the Mediterranean regions, the Muscat was grown in Spain and the Corinth grapes in Greece. The sultana grapes were cultivated around Persia, Turkey, Iran and Iraq.
Raisins were in great demand. The Romans and Greeks realized that not only were raisins delicious, but they were the ideal energy food, specially if you had to cross the Alps or travel long distances conquering people.
Viticulture became very important in Europe, particularly in Spain. Which is how grapes got to America. The very first boats to arrive with the Spanish Conquistadors, and their missionaries, had their holds full of vine shoots to be planted in the Americas.
Grapes, before drying are almost 80% water, the aim is reducing this water content to 15%, but no more or else you end up with pellets. You need about 5 lbs of grapes to make 1lb of raisins.
Sun-dried raisins are just that: grapes which have been dehydrated in the sun. To achieve this either you place them on special paper on elevated trays of thin wooden laths . Or the grapes intended for raisins are grown on a trellis system supported by wires. The sun-drying process in both cases takes about three weeks. You can also dry them in ovens. Golden raisins are golden because of the process they undergo, not because they are a different variety of grape. This process consists in first giving them a bath with water and sulfur dioxide (did I just say a bad word?) to preserve the light color, and then they are air dried.