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Jigme Singye Wangchuck, the fourth Druk Gyalpo of Bhutan, reigned from 1972 to 2006. He was instrumental in modernizing Bhutan and guiding the country towards democracy. Under his leadership, Bhutan transitioned from an absolute monarchy to a constitutional monarchy, and he established the country's first National Assembly in 2008. Wangchuck's reign is widely regarded as a period of significant progress and development for Bhutan.