The best way to enter is by Druk Air or Bhutan Airlines. These airlines connect Paro, Bhutan with the following countries :
India : Delhi, Kolkata, Baghdora, Guwahati, Gaya
Nepal : Katmandu
Thailand : Bangkok
Bangladesh : Dhaka
If you are to combine your trip to Bhutan with a visit to nearby Indian States of West Bengal, Sikkim and other northeastern States, you might want to enter or exit through a border town.
(1). Phuntsholing – It is also possible to enter/exit Bhutan through Phuntsholing, the south-western Bhutanese border. Bagdogra in the state of West Bengal (India) is the nearest airport. (NJP) New Jalpaiguri Station near Bagdogra, West Bengal, is also another railway station if you are traveling by train. It connects with major cities in India. If travelers wish to visit Indian state of Sikkim, Kalimpong & Darjeeling (West Bengal), Phuntsholing is the most convenient point of entry/Exit. You can even combine 1-2 nights halt at a Jaldapara Wildlife Sanctuary (15 km from Phuntsholing), West Bengal.
(2). Samdrup Jonkhar – Exit from Bhutan can be made through Samdrup Jonkhar also. This Frontier Bhutanese town is approximately 3 hours drive from Gauhati, capital of Indian north eastern state of Assam and can be combined with a trip to the Kaziranga Wildlife Sanctuary, Assam. A highway that will connect India with Myanmar (Burma) and Thailand is already under construction and will open in 2005, a good connection towards east asia.
As per Bhutan government´s policy, it is mandatory to travel at least one way by Druk Air; it can be either entry or exit or both ways. However, if Druk Air seats are full, then, both ways by road is permitted.