The Kingdom of Thailand is governed by a constitutional monarchy with a parliamentarian form of governement.  The current monarch, King Bhumibol Aduluadej, Rama IX, is of the Chakri dynasty.  This dynasty has reigned Thailand since 1782.  King Rama I founded the Kingdom's new capital, Bangkok, on the banks of the Chao Phraya River that same year.  And that was the beginning of the Rattanakosin or Bangkok period.
 

                For further details on the Chakri dynasty and each of our nine Kings please got to
http://mucc.mahidol.ac.th/Thailand/monarchy/chakri