The Kingdom of Bhutan is a landlocked country in the Eastern Himalayas of South Asia, bordered by Tibet and India. Bhutan is the second least populous nation in South Asia after the Maldives, and has never been colonised in its history, having endured independently for centuries. Situated on the ancient Silk Road, the Bhutanese state developed a unique and distinct national identity based around Buddhism, headed by a spiritual leader known as the Zhabdrug Rinpoche and initially governed as a Buddhist theocracy comprised of many fiefdoms. A civil war in the 19th century led to the rise of the House of Wangchuck and the establishment of ties with the British Empire and India. Bhutan's capital is Thimphu, the largest city in the country, and it transitioned from an absolute monarchy to a constitutional monarchy in 2008. Bhutan is notable for its pioneering of the concept of 'gross national happiness', though it is also one of the most isolated and least developed countries in the world.