The history of Siam prior to the fourteenth century A.D. is chiefly known from a hodgepodge of disconnected stories and fragments known as the "Pongsawadon Mu'ang Nu'a" ("Annals of the North Country"), compiled at different periods from such of the official records of various cities and kingdoms as had escaped the destruction which at intervals overtook the communities to which they referred. With the omission of the numerous supernatural happenings there recorded and comparative study of the chronicles of neighboring countries, scholars have been able to draw a rough picture of the condition of Siam at the dawn of historical time.

Their researches show a country inhabited by primitive people of Mon-Khmer stock among whom had settled groups of their more civilized cousins from Cambodia, who had brought with them the religion and customs acquired by contact with colonists from India. These communities grew from villages into cities and at the same time sent out offshoots in all directions, which in time became the capitals of small states, the chiefs of which constantly made war on each other and against the Lao-Tai tribes at their borders and now and again rose to sufficient strength to repudiate the vague suzerainty claimed over them all by the empire of Cambodia.

Contemporary records of the period subsequent to the fourteenth century A.D. are easily available. The most important is the "Pongsawadon Krung Kao" ("Annals of the Old Capital" or "Annals of Ayuthia"), which contains a complete and fairly accurate account, compiled in successive reigns, of the history of the country from A.D. 1349 to 1765. The seventeenth and later centuries have also seen the production of numerous works, by European travelers and missionaries, which deal wholly or partly with Siam.