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 centralized control. Many such ''dzong'' still exist and are active centers 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.