These vessels are made by skilfully hollowing out a single piece of wood. Much attention is paid to their elegant shapes as well as to the decorative incisions into the surface. The purpose of the containers is both for the storage and fermentation of milk. Fermentation is a way of extending the lifespan of milk which is crucial to nomadic peoples and in times of drought or scarcity. Certain woods are identified as containing the correct enzymes necessary to aid this fermentation process. Wood is also a scarce resource and thus the vessels are repaired with either cow dung plugs or with found or recycled pieces of metal. The mending materials are often applied in a decorative way which attests to the value of the vessels within the society.