Archaeological evidence suggests Bhutan was inhabited as early as 1500–2000 BC by herding animals. By 8th century a lotus born saint Padmasambava introduced Buddhism in Bhutan, and Buddhism has become an integral part of the culture of Bhutan. Before the arrival of Shabdrung Ngawang Namgyal, from Tibet to Bhutan, the political arena was fragmented between many local chiefs, each controlling his own territory and engaging in petty feuds with the others. But the arrival of Zhabdrung Nawang Namgyal in 1616 A.D. has brought the most significiant era in the history of Bhutan. Over the next thirty years, he unified the country under his central leadership, which otherwise was fragmented into petty principalities, ruled over by the tribal feudal chiefs. Shabdrung established himself as the country’s supreme leader. He ruled over Bhutan for thirty-five years until his retirement in 1651 A.D. During his reign of 35 years, he built dzongs (fortress), monasteries, and religious institutions. He established the Drukpa Kargyupa school of Tantric Mahayana Buddhism in Bhutan. His reign was marked by the introduction of the dual system of governance called the Chhoesid Nyigden. This new system was characterized by the sharing of power and authority between the Desi who was the head of secular affairs and the Dharma Raja or the spiritual head, called as Je Khenpo . He also codified laws for the country. The laws were based on medieval theocratic principles called the Tsa-Yig. The successive ‘Dharma Rajas’ were the incarnations of the Shabdrung whereas the post of the Deb Raja was like that of the Prime Minister. In course of time, the Dharma Rajas preferring religious matters withdrew themselves into seclusion while the Deb Rajas consolidated their authority exercising sole responsibility over the secular affairs. The dual form of governance continued until the birth of the Wangchuk dynasty and establishment of hereditary Monarchy in 1907, when Ugyen Wangchuck was elected as the first hereditary monarch of Bhutan on December 17, 1907. The absolute monarchy continue until the fourth king Jigme Singye Wangchuk abdicated the Throne to his eldest son, Jigme Gesar Namgyal Wangchuk, the fifth king of Bhutan, who is responsible for Bhutan’s transition from absolute monarchy to democratic constitutional monarchy in 2008, and held the first parliamentary election in the same year.