The major economic theory that dominated the late 19th and early 20th centuries regarding global trade was "Mercantilism," though it was increasingly challenged by "Liberalism" and "Comparative Advantage." Mercantilism emphasized the importance of accumulating wealth through trade surpluses, government intervention, and the expansion of national power. However, as globalization evolved, the principles of classical economics began to take hold, advocating for free trade and minimal government involvement in the economy. Figures like David Ricardo promoted the idea of comparative advantage, suggesting that countries should specialize in producing goods they can create most efficiently, thus enhancing overall economic welfare through trade.