Postage stamps and postal history of Bhutan
The first postage stamps of Bhutan were issued in 1962, the same year that the first motorable road was opened. Before that there was a mail delivery system in place for official mail using mail runners, and between 1955 and 1962 revenue stamps were accepted as payment for internal mail.
Source: Wikipedia — Postage stamps and postal history of Bhutan (CC BY-SA 4.0)