The Vajrayana school of Buddhism spread to Bhutan from the Pala Empire of Bengal.
Zhabdrung Ngawang Namgyal unified the valleys of Bhutan and established a theocratic government.
Bhutan ceded the Bengal Duars to British India during the Duar War.
The Treaty of Punakha guaranteed British advice in foreign policy in exchange for internal autonomy.
Bhutan signed a treaty with India recognizing each other's sovereignty.
Bhutan officially joined the United Nations.
The 2008 Constitution established a parliamentary government in Bhutan.