Pre-Hoabinhian stone industry in Upper Palaeolithic cave sites around the Red River valley of northern Vietnam. It is regarded as the immediate predecessor (or an early stage) of the Hoabinhian and of late Pleistocene date c 18,000-9000 BC. It is characterized by unifacially flaked pebbles, some bifacially worked pebbles, choppers, side-scrapers, and 'round-edged' pebbles. Son Vi is the type site of this industry.