Archeology can still tell us little of the first human occupants of Siam. The earliest evidence of man's existence here is furnished by celts, uncovered in the Peninsula and on the eastern plateau, which are supposed to date from the later Neolithic period; geology, however, gives us no reason to conclude that the makers of these implements were not preceded by other races.

[Illustration: 1. The rivers fall from the northern plateaus to the central plain through narrow defiles.]

[Illustration: 2. Ancient wall at Chiengmai. The city walls are preserved as picturesque ruins.]

[Illustration: 1. An international incident was caused by the European alpinist who first scaled the monolith to plant his nation's flag upon it.]

[Illustration: 2. Boats must be pulled upstream through the rapids by ropes.]

[Illustration: 1. The valuable gum resin, Bengal kino, is yielded by the "mai kwao" (Butea frondosa).]

[Illustration: 2. Young rice plants are transplanted from a seedbed to the flooded fields.]

[Illustration: 1. At the end of the rains, fish may be captured from the roadsides.]

[Illustration: 2. Cows and water buffaloes are treated as family pets.]

Among the mountains of the Malay Peninsula exist to this day small groups of dwarf, black-skinned, kinky-haired people, different from all other races of the country but closely related to the natives of the Andaman Islands and the Negritos of the Philippines; it has been surmised that these Ngo (Semang) are the dwindling remnant of a once numerous population, successors to (and possibly descendants of) the Neolithic men.

Following the Ngo and sometime during the past few millennia, it is believed that there came successive waves of a people of Mongolian origin who, making their way down the rivers, drove the primitive Negritos into the hills and settled in their place. Now conveniently known as the Mon-Annam family, their descendants are the Mon (Peguans), the Cambodians, and the Annamese, as well as numerous semibarbarous lesser tribes which persist among the mountains of the subcontinent.

Probably between two and three thousand years ago and certainly after the arrival of the Mon-Annam immigrants, another great population wave, known as the Tibeto-Burman family, rolled southward over Indo-China but chiefly descended the valley of the Irrawaddy (where they have given rise to the modern Burmese), thus scarcely entering Siam at all. Only in comparatively recent times, driven from their former homes by political disturbances, have tribes of this stock (Yao, Meo, etc.) migrated into Thailand and the territories to the east, where they are constantly being joined by others of their blood brothers from farther north.

While the Mon and the Khmer (Cambodians) were still spreading over the southern parts of Indo-China and before they had begun, under the influence of colonists from India, to emerge from a condition of savagery, the tribes which they had left behind them at different points during their southward movement were already being driven back into the mountains and brought into a state of partial subjugation by the members of a third great family of migrants from the north. These were the people now known as Lao-Tai, who, sending out bands from their ancient seat in the valley of the Yangtze, had already, 2,500 years ago, established a powerful state on the banks of the Me Khong in the neighborhood of the modern Wieng Chan (Vientiane).

The Lao-Tai of the Yangtze Valley were evidently very numerous, for not only did they thus early establish kingdoms far from home but also became a power in their own land and for some time bid strongly for the mastery of all China. For centuries they waged successful wars on all their neighbors, but their strong propensity for wandering weakened their state and finally caused its disintegration. The Chinese attacked them repeatedly, each attack producing a fresh exodus until, during the thirteenth century A.D., the Emperor Kublai Khan dealt them a final blow which crushed their power and scattered them in all directions. Fugitives entered Assam, where earlier emigrants had already settled, and became the dominant power in that country; others invaded Burma, where for two centuries a Lao-Tai (Shan) dynasty occupied the throne; while down the Salwin and Me Khong Valleys came band after band of exiles who mingled with their cousins already established in those valleys and, in time fusing with the Mon and the Khmer, produced the race which, since the founding of the city of Ayuthia, has been dominant in Siam.

The principal divisions of the Lao-Tai family now living within the borders of Siam are the Thai ("free men") or Siamese proper; the Lao, who occupy the former seats of those tribes of their own stock that afterward developed into the Thai; and the Shans, a later intrusion of distant cousins, descended from the Lao-Tai tribes that settled in the more eastern districts of Burma in the twelfth century and earlier.