Until 1974, Bhutan was closed to the outside world. Now people can visit the country, but only in small numbers. The only airport is in Paro District. The country is bordered on the south by the Republic of India and on the north by China. The Indian state of Sikkim separates Bhutan and Nepal. The main export of Bhutan is hydroelectricity which is sold to India. The economy of Bhutan is very small but is growing quickly. The currency is the Ngultrum, which is pegged at par with the Indian rupee.