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. KINGDOM OF SUKHOTHAI-SAWANKHALOK The most ancient Mon-Khmer settlement of which anything definite is known was Sukhothai (located on the river Me Yom some 200 miles north of the site of modern Bangkok), which by 300 B.C. was already a sizable village. At first putting forth no pretensions to the status of kingdom, the community evidently increased rapidly in importance, for some two centuries later the chief, Phraya Thammarat, declared himself King of the district, founded the new capital of Sawankhalok, and appointed one of his sons viceroy of Sukhothai, which itself soon grew into a fortified city. Thereafter, the two towns served alternately as the capital of a country which, as the Kingdom of Sukhothai-Sawankhalok, gradually grew to great wealth and strength. Its monarchs occupied themselves with the waging of war against the petty chieftains of neighboring states (founded in the same manner and upon the same principles as their own but at somewhat later dates) and, in course of time reducing all of them to vassalage, came to be recognized as rulers of the whole country. The vague overlordship of Cambodia continued for many centuries but with little or no influence upon the destinies of its nominal dependency, which was left to manage itself and its own subordinates as seemed to it best. At the same time as the various Mon-Khmer states of Siam were struggling to subdue each other, the Lao tribesmen inhabiting the mountainous districts to the north, emboldened by their increasing numbers and constantly raiding the rich villages of the plains, were demanding an ever greater amount of attention and as early as the fifth century A.D., the reduction of the Lao had become almost the main preoccupation of the kings of Sukhothai-Sawankhalok. Expeditions against them were constant, but while they were frequently defeated and large numbers of them carried captive to Sukhothai or Sawankhalok, the intercourse thus brought about served only to strengthen them, since it enabled them to adopt the customs and civilization of the conquerors and then turn the acquired knowledge against their instructors with an ever-growing degree of success.