political and religious landscape, eventually leading to the ascendancy of the Drukpa Lineage by the 16th century. Locally, Bhutan has been known by many names. The earliest Western record of Bhutan, the 1627 Relação of the Portuguese Jesuits Estêvão Cacella and João Cabral, records its name variously as Cambirasi (among the Koch Biharis), Potente, and Mon (an endonym for southern Tibet). Until the early 17th century, Bhutan existed as a patchwork of minor warring fiefdoms, when the area was unified by the Tibetan lama and military leader Ngawang Namgyal, who had fled religious persecution in Tibet. To defend the country against intermittent Tibetan forays, Namgyal built a network of impregnable dzongs or fortresses, and promulgated the Tsa Yig, a code of law that helped to bring local lords under centralised control. Many such dzong still exist and are active centres of religion and district administration. Portuguese Jesuits Estêvão Cacella and João Cabral were the first recorded Europeans to visit Bhutan in 1627, on their way to Tibet. They met Zhabdrung Ngawang Namgyal, presented him with firearms, gunpowder and a telescope, and offered him their services in the war against Tibet, but the Zhabdrung declined the offer. After a stay of nearly eight months Cacella wrote a long letter from the Chagri Monastery reporting on his travels. This is a rare extant report of the Zhabdrung. When Ngawang Namgyal died in 1651, his passing was kept secret for 54 years. After a period of consolidation, Bhutan lapsed into internal conflict. In 1711, Bhutan went to war against the Raja of the kingdom of Koch Bihar in the south. During the chaos that followed, the Tibetans unsuccessfully attacked Bhutan in 1714. In the 18th century, the Bhutanese invaded and occupied the kingdom of Koch Bihar. In 1772, the Maharaja of Koch Bihar appealed to the British East India Company which assisted by ousting the Bhutanese and later attacking Bhutan itself in 1774. A peace treaty was signed in which Bhutan agreed to retreat to its pre-1730 borders. However, the peace was tenuous, and border skirmishes with the British were to continue for the next hundred years. The skirmishes eventually led to the Duar War (1864–65), a confrontation for control of the Bengal Duars. After Bhutan lost the war, the Treaty of Sinchula was signed between British India and Bhutan. As part of the war reparations, the Duars were ceded to the United