The term "globalization" has been used by economists since the 1980s although it was used in social sciences in the 1960s; however, its concepts did not become popular until the latter half of the 1980s and 1990s. The earliest written theoretical concepts of globalization were penned by an American entrepreneur-turned-minister Charles Taze Russell who coined the term 'corporate giants' in 1897.[6] Globalization is viewed as a centuries long process, tracking the expansion of human population and the growth of civilization, that has accelerated dramatically in the past 50 years. Early forms of globalization existed during the Roman Empire, the Parthian empire, and the Han Dynasty, when the Silk Road started in China, reached the boundaries of the Parthian empire, and continued onwards towards Rome. The Islamic Golden Age is also an example, when Muslim traders and explorers established an early global economy across the Old World resulting in a globalization of crops, trade, knowledge and technology; and later during the Mongol Empire, when there was greater integration along the Silk Road. Globalization in a wider context began shortly before the turn of the 16th century, with two Kingdoms of the Iberian Peninsula - the Kingdom of Portugal and the Kingdom of Castile. Portugal's global explorations in the 16th century, especially, linked continents, economies and cultures to a massive extent. Portugal's exploration and trade with most of the coast of Africa, Eastern South America, and Southern and Eastern Asia, was the first major trade based form of globalization. A wave of global trade, colonization, and enculturation reached all corners of the world. Global integration continued through the expansion of European trade in the 16th and 17th centuries, when the Portugues ...