The Longido District in northern Tanzania—part of the traditional homeland of the Maasai people—stretches along the Kenyan border, from the slopes of Mt. Kilimanjaro in the east, to Lake Natron in the west. It is a rugged but beautiful region, dotted with parks and wildlife reserves, not far from the wide plains of Serengeti National Park and its endless herds of hooved animals. The climate ranges between arid to semi-arid, with low seasonal rainfall and severe drought conditions in recent years. For the Maasai, pastoralism has long been the predominant way of life, with young Maasai men traveling long distances away from their families in search of grazing areas and water sources. But in recent years, economic hardship has forced many Maasai to relocate in cities and towns, where greater interaction with urban populations has brought them in closer contact with a problem that plagues the entire country: HIV.