An kafa Masarautar Rattanakosin a cikin 1782 tare da kafa Rattanakosin (Bangkok), wanda ya maye gurbin birnin Thonburi a matsayin babban birnin Siam.Matsakaicin yankin tasirin Rattanakosin ya haɗa da jahohin vassal na Cambodia , Laos , Shan Jihohin, da kuma arewacin Malay.Rama I na Daular Chakri ne ya kafa Masarautar.Rabin farko na wannan lokacin yana da alaƙa da haɗin gwiwar ikon Siamese a tsakiyar yankin Kudu maso Gabashin Asiya kuma ya kasance a cikin gasa da yaƙe-yaƙe don samun yancin yanki tare da masu adawa da Burma da Vietnam .^[56] Lokacin na biyu shine ɗayan haɗin gwiwa tare da turawan mulkin mallaka na Biritaniya da Faransa wanda Siam ya kasance ƙasa ɗaya tilo a kudu maso gabashin Asiya don ci gaba da 'yancin kai.^[57]A ciki Masarautar ta samu ci gaba ta zama kasa mai tsattsauran ra'ayi, mai kishin gaskiya, kasa mai iyaka da aka ayyana ta hanyar mu'amala da kasashen yamma.An yi wannan lokacin ne ta hanyar ƙara yawan ikon masarautar, da kawar da ikon ma'aikata, miƙa mulki ga tattalin arziƙin noma, faɗaɗa iko kan jihohin da ke nesa, da samar da asalin ƙasa ɗaya ɗaya, da bullowar tsakiyar birane. aji.Duk da haka, rashin aiwatar da gyare-gyaren dimokuradiyya ya ƙare a juyin juya halin Siamese na 1932 da kafa tsarin mulkin tsarin mulki.