150 Baht - Rama IX Rajamangala Celebrations

Issued to mark the Rajamangala ceremony, the royal rite performed when a Thai king has reigned longer than the most venerable previous monarch. Bhumibol Adulyadej surpassed the reign of Rama IV in 1988, making him the longest-reigning monarch in Thai history at that point — a threshold with genuine ceremonial weight in a country where royal longevity carries direct religious significance under Theravada Buddhist tradition.