There is not much documentation about the history of Bhutan because of its long isolation from the rest of the world. New explorations have suggested about the presence of men around this region in 2000 BC, but written history dates back to the 2nd century AD. Buddhism was introduced in Bhutan in the 8th century when Buddhist monk Guru Padmasambhava came to Bhutan and established many monasteries. The Drupka sub-sect of Kagyud school of Mahayana Buddhism was established by scholar Padmalingpa in the 15th & 16th century. The growth of Drupka sect also led to the establishment of the theocracy of Druk-yul by Shabdrung Ngawang Namgyal in 1616.
Shabdrung is regarded as the person who unified the kingdom of Bhutan and built some remarkable temples & forts known as Dzongs. He also started the dual system of secular and spiritual leaders that was ended by Sir Ugyen Wangchuk in the late 19th century. He became the first hereditary king of the country.