A Nyangatom boy holds a cow whilst another boy draws his bow ready to fire an arrow with a very short head into the artery of the cow so they can bleed it. Several pints of blood will be collected which will then be mixed with milk and drunk by the Nyangatom. The Nyangatom or Bume are a Nilotic tribe of semi-nomadic pastoralists who live along the banks of the Omo River in south-western Ethiopia.