The Bhutan remained largely cut off from the rest of the world up until the early 1960’s however now, it is opened for the travelers and there is mainly two way to enter Bhutan one is by overland and once by flight.
Get Bhutan by flight
There are flights available from Nepal, Thailand, India, Bangadesh and Singapore so, you can take flight to Bhutan from one of these destinations.
Get Bhutan by Land
You can enter Bhutan by land and one of the most popular entry point is the town of Phuentsholing in south-west from Darjeeling, India and is located approximately 170 km east of the Indian national airport at Bagdogra and after crossing Phuentsholing border, you begin your journey to Thimphu, the capital city of Bhutan and it takes about six hours for the 170 km. stretch.