The southernmost part of Vientiane's Hadsayfong District, located some 25 kilometres south of Vientiane city centre, forms almost a peninsula at a sharp bend in the Mekong River. This area has long been known for its fertile soil and generous water supply, which makes it possible to grow a large range of different produce and ensures an abundant harvest. More than 30 vestiges, most believed to be of Mon origin, may be found within the vicinity of the modern villages of Sayfong Neua and Ban Sayfong Tai, including temple foundations, stupas, water tanks, wells and an extensive canal system. Remains of the oldest temples have been dated to the 11th century, indicating that Buddhism was already established here by that time. Ancient Sayfong was clearly a very important religious centre, since according to local legend it contained no fewer than 300 temples, 220 of them in the region of Sayfong Neua and the remainder on the opposite bank of the Mekong in present-day Thailand. Recent excavations undertaken jointly by the Lao National Museum, the Department of Museums and Archaeology of the Ministry of Information and Culture and Upssala University, Sweden have revealed that Sayfong retained its importance until the 16th century, and even today southern Hadsayfong District has an unusually large quota of temples per square kilometre; many of these, like Wat Pa Meta, Wat Pa Chaoxang and Wat Pa Leilay, have been built directly onto the foundations of 11th century structures, indicating that the old temple sites are still of great importance to the people of the area. Its very close proximity to Vientiane suggests that Sayfong may have been closely linked to the ancient city of Candapuri (Chanthaburi). Unfortunately many artefacts were removed from the area during the French and Royal Lao Government periods, but a few have remained in the country. Of particular interest are the Khmer artefacts which have been unearthed here, including the so-called 'Sayfong Stone', a foundation stone (now housed in Ho Phra Keo National Museum) which records in Khmer the establishment of a hospital by King Jayavarman VII (1181-1218), prompting some scholars to claim that Sayfong was in fact a Khmer city. It is known that by the 11th century the power of the Mon had been eclipsed by that of the Khmer throughout the wider region, but it is not yet clear whether Mon city-states such as Sayfong came under direct Khmer governance during this period, or simply paid tribute to a powerful Khmer overlord who occasionally sponsored the establishment of hospitals and religious edifices within their territory.