As a historically nomadic and then semi-nomadic people, the Maasai have traditionally relied on local, readily available materials and indigenous technology to construct their housing. The traditional Maasai house was in the first instance designed for people on the move and was thus very impermanent in nature. The Bomba (houses) are either star-shaped or circular, and are constructed by able-bodied women. The structural framework is formed of timber poles fixed directly into the ground and interwoven with a lattice of smaller branches, which is then plastered with a mix of mud, sticks, grass, cow dung, human urine, and ash. The cow dung ensures that the roof is waterproof. The enkaj is small, measuring about 3x5 m and standing only 1.5 m high. Within this space, the family cooks, eats, sleeps, socializes, and stores food, fuel, and other household possessions. Small livestock are also often accommodated within the enkaji. Villages are enclosed in a circular fence (an enkang) built by the men, usually of thorned acacia, a native tree. At night, all cows, goats, and sheep are placed in an enclosure in the centre, safe from wild animals.