Thailand's ruling family.
Phraphutthayotfa Chulalok (1737–1809) founded the dynasty and ruled as Rama I (r. 1782–1809). He reorganized Siam's defenses to successfully repel numerous Burmese attacks. His descendants have reigned in an unbroken line ever since. Rama III (r.1824–51) increased trade with Europe and negotiated a treaty with the British East India Co. ; King Mongkut (Rama IV; r.1851–68) and King Chulalongkorn (Rama V; r.1868–1910) helped modernize the government along Western lines and thereby avoided colonial rule. King Vajiravudh (Rama VI; r.1910–25) instituted social reforms and restored the nation's fiscal autonomy (lost to the West under Rama IV). Bhumibol Adulyadej (Rama IX) has reigned since 1946 as Thailand's ceremonial head of state.