With fewer than 100 individuals remaining in the wild in Vietnam the Critically Endangered western black crested gibbon Nomascus concolor is one of the rarest primates in Vietnam, a country with 90% of its 25 primate species categorized as threatened. The last bastion for the species in Vietnam is the forest of Muong La–Mu Cang Chai. The 5,000 ha of forest in Muong La District, Sonla Province, north-west Vietnam, are currently designated as Watershed Protection Forest. This, and the 20,000 ha of contiguous forest in the neighbouring Mu Cang Chai Species and Habitat Conservation Area, is home to Vietnam's largest and probably only viable population of western black crested gibbon. The most recent survey of the area recorded at least six gibbon groups in Muong La and at least another 14 groups in Mu Cang Chai, with a minimum population of 59 individuals.

Fauna & Flora International (FFI) has been working in Muong La since 2002, establishing and continuously supporting three community conservation teams, conducting biodiversity and gibbon surveys, carrying out awareness-raising and environmental education activities and developing a locally-based species conservation action plan for the gibbons at this site. FFI's work has helped protect not only this gibbon but several other nationally and internationally important species for which Muong La–Mu Cang Chai Forest is home, including significant populations of the grey langur, rufous-necked hornbill and Temminck's tragopan.

Because of its experience with biodiversity monitoring and protection FFI Vietnam has been asked by its project partners in the Sonla and Muong La Forest Protection Departments to assist in carrying out the activities required to upgrade the forest to Muong La Species and Habitat Conservation Area. Ten years ago FFI supported Yen Bai Province in establishing the Mu Cang Chai Species and Habitat Conservation Area. Since then FFI's conservation efforts in the area have advanced and Mu Cang Chai is the first protected area in Vietnam for which a national policy was developed to allow collaborative management, ensuring local communities have a role in the management of the forest on which they depend.

FFI's work in Vietnam is currently supported by the Critical Ecosystem Partnership Fund, McKnight Foundation, Twycross Zoo, Fota Wildlife Park and Hanoi-based donors such as Handspan Adventure Travel and Haivenu Tours. In June 2012 FFI secured a grant from the US Fish & Wildlife Service to support work in Muong La and Mu Cang Chai. Activities under this grant will comprise improved law enforcement, scientific data collection and educational activities. However, with the imminent establishment of the Muong La Species and Habitat Conservation Area, FFI will have to increase its conservation efforts at this site further by assisting with the construction of ranger stations and boundary demarcation, and as soon as a protected area management board is established FFI will concentrate its efforts on establishing a Management Advisory Committee.