Well, the problem with treating globalization as starting before 1492 is that any system of international trade is necessarily going to be limited to either Africa+Eurasia or the Americas. So "Global" is a bit of a misnomer.

I've just started 1493 by Charles C Mann and finished 2 others about this very topic, but I am in no way an historian so someone please correct me if I'm wrong. For centuries goods from the east made their way west by different routs, the silk road for example, but I would say a good chunk of goods came by water. I'm not sure about the 13th century, but by the mid 15th the Turks controlled trade going to Europe, along with monopolies in the Mediterranean by Venice and Genoa, by the time goods got there they were very expensive. This system all changed when Mehmet II conquered Constantinople in 1453 and closed the trade routes. Later in the century Portugal was fighting for control of Morroco and began to sail further south along Africa's west coast, finding gold and slaves. They managed to sail around Africa and into the Indian ocean and after some fighting and cajoling started bringing cargo back to Portugal. A few years before Columbus had found land by sailing west, what he was convinced was outlying Asian islands but most likely the Bahamas. Bickering between the two monarchs about who owned what caused the "catholic kings" to ask the pope to settle the matter. Years before another pope had granted exclusive rights to Portugal but now it was decided by the infamous Borgia pope Alexander VI to split the world in half, drawing an imaginary line through the globe, giving everything east of the line to Portugal, covering their route around Africa, and everything west to Spain. Later, in 1494, the treaty of Tordesillas moved the line west a bit, important because Brazil now fell into Portugal's control. But where did the line fall on the opposite side of the world? Both claimed exclusive rights to the "Spiceries" but nobody could say where the line fell exactly, causing much war and conflict for centuries to come. After a while the other European nations start to encroach on their monopolies, the English and Dutch raiding Spanish galleons heading back to Spain loaded with American gold and silver. The silver also was highly prized by China.

OK , so after this long, rambling answer, let me try to answer your question. Globalization was a long and drawn out process, probably not recognized as such by those forwarding it and not really their intention. The goals were spices, gold and slaves, trade, and bringing Christianity to the pagans. In fact, one of the first missions of Vasco De Gama was to find the legendary (Christian) king Prester John to enlist his help clearing out Muslims from the eastern Mediterranean so they could control the trade. I would argue that globalization IS a modern phenomenon even if the seeds were planted centuries ago. I guess all this rambling explains is the topic is complicated but I personally think it started before the 18th century.

I welcome any and all corrections, I'm not as well read on these centuries as I am on earlier times.

The last crusade by Nigel Cliff 1494 by Stephen R Bown

It seems to me the answer would depend on how you define globalization. There have been trade networks crossing thousands of miles going as far back as the Indus Valley and Mesopotamian civilizations. We know because archaeologists have found artifacts of one culture in the other's region.

However this trade was usually in luxuries, and largely affected only the wealthy elites of these societies. Necessities tend to be domestic, as peoples generally want to be in control of their own ability to stay alive.

So when did developed (relative to their time) societies begin routinely sourcing necessities like food stuffs and vital mineral resources from outside their homelands? If anyone has an answer to this question, I'd say that's when globalization (as a phenomenon separate from regular old international trade) started.