Underwater excavations in the Mekong Delta have recovered a set of jade-bound ritual gongs belonging to a previously unidentified Iron Age culture. These bronze instruments, reinforced with jade bands, were likely used in large-scale "Monsoon-Calling" festivals designed to ensure the arrival of life-giving rains for rice cultivation.
The acoustic properties of the gongs were optimized for over-water transmission, suggesting that the festivals were conducted on barges or platforms within the river system. This find significantly predates known Buddhist water festivals, revealing a deep-seated indigenous tradition of hydraulic spirituality in Southeast Asia.