The Rwandan refugee crisis in mid-1994 led to the influx of more than 600,000 people into the Ngara District of northwest Tanzania. Considerable environmental damage was caused by refugees harvesting firewood and building poles, poaching in the Burigi and Biharamulo Game Reserves, and the use of cheap refugee labour in charcoal and timber operations. Refugees also put some 15,000 hectares of land under cultivation in Ngara alone.