The Mekong River valley through China, Thailand, Laos, Cambodia and Vietnam formed one of the largest migrational zones. Beginning as early as the 8^th century AD, but most certainly by the 10^th century, migrant Tais had established local meuang (roughly 'principality' or 'city-state') -- each based in a river valley -- under the rule of sovereigns called chao meuang. Although Tai social schemata dominated, such states were not exclusively Tai in population, but assimilated indigenous populations of Tibeto-Burmans and Mon-Khmers.

One of the most important cultural mainstays of the region, Buddhism, may have entered the region as early as India's Ashoka period, in the 3^rd or 2^nd century BC, when Indian missionaries are said to have been sent to a land called Suvarnabhumi (Land of Gold). Suvannabhumi likely corresponds to a remarkably fertile area stretching from southern Myanmar, across central Thailand, to eastern Cambodia. Two different cities in Thailand's central river basin are still called Suphan Buri (City of Gold) and Ang Thong (Reservoir of Gold). Buddhism remains the major religion in all five Mekong Basin countries, flourishing in a myriad variety of schools and sects.

Wherever these meuang sprang up, natural and man-made waterways served not only as sources for nutrition, bathing, agriculture and transport, but as important cultural adjuncts. City plans in virtually all these river valley states originally resembled mandala, the quasi-circular diagrams created by Buddhist artists as meditation objects. Much like Hindu-Buddhist mythology's Mount Meru, around which the cosmos unfolds in concentric continents alternating with slender cosmic oceans, river valley states were organized around a web of natural and artificial waterways fanning out from a central river or stream serving as the city axis.

The most important festival in the entire region is the celebration of the solar-lunar new year, when the sun passes from the sign of Pisces into the sign of Aries in the zodiac. Calling it Samkranta (Sanskrit for 'fully passed over', pronounced 'Songkran' in Tai-speaking cultures and 'Thingyan' in Myanmar), believers hold that during this short period -- three to five days depending on the country -- the spirit of the previous year departs and a new one arrives. Thus this festival demands that everyone take a few days out of their normal work schedules for spiritual cleansing and renewal.

Water, representing the principal agent for this cleansing and renewal, plays a central role throughout the festival, and in fact a common nickname for Samkranta nowadays is the 'water festival'.

Although the original meaning of the water festival is kept alive by ceremonies such as these, nowadays it's also very much a festival of fun. In most of the Greater Mekong Sub-Region, this is the height of the hot and dry season, and residents revel in being able to douse one another with cold water to cool off. Foreign visitors are not exempt from the soaking, so watch out!

Food and ways of eating also tie together the cultures of the Mekong. Thought to be the world's first rice cultivators, Tais carried rice with them wherever they went during their early migrations throughout China and Southeast Asia. The vast and fertile Mekong Basin has suited rice-growing so well that today the region is the largest exporter of rice in the entire world. The grain has become so central to Mekong food culture that the most common term for `eat' in all five Mekong countries is literally `consume rice'.

Philosopher-architect Buckminster Fuller believed the prevalence of the city plans favouring land-alternating-with-water suggested an Oceanic origin for the peoples of Southeast Asia and southwestern China. The regional preference for at least one fish dish at virtually every meal, and the seasoning of many dishes with fermented fish sauce, contributes further evidence for the Oceanic theory. Denizens of the Mekong Basin also show a strong liking for dishes enlivened by chilli peppers, a seasoning staple that originally arrived via Portuguese ships sailing from the Americas.

The textures and colors of life among the shared Mekong cultures also come alive in regional textile traditions. This vibrant cultural heritage, expressed in silk and cotton fabrics in the form of skirts, shawls, shoulder bags and wall hangings, links the immediate present with the distant past in an unbroken lineage of weaving styles. Techniques such as discontinuous and supplementary weft, weft ikat and interlocking tapestry create rich patterns that are not only a treat for the eyes but are full of shared cultural symbolism. Yantra (geometric patterns with magico-religious intent) such as the Tantric diamond, and mythical animal motifs such as the naga (river dragon) provide protection from malicious spirits, while elephant and lion motifs impart blessings upon the owner.

The Buddhist stupa may be the most potent single artistic symbol linking the cultures of the Mekong Basin. An explicit regional representation of Mount Meru, the mythical mountain sitting at the centre of the Hindu-Buddhist cosmological universe, these tapering towers can be found in virtually every corner of the Mekong region. Some stupas, such as the great chedi at Wat Arun in Bangkok or the zedi at Ananda Pahto in Bagan, were consciously designed to imitate the Meru model, with a tall central stupa surrounded by four satellite stupas. Many others, such as the more vertical tap of Vietnam, are much more abstract representations. Originally hailing from India, these marvels of brick, stone or wood proved so compelling that their construction eventually spread to East Asia and beyond.

In spite of the rise of modern sovereign nation-states in the Greater Mekong Sub-Region, cultural exchange spurred by a centuries-old shared heritage flows unimpeded.