Video. The source of their power – a large ancestral drum, the ngadji, is in storage in a museum in London. … The Pokomo people of Kenya’s Tana River valley once worshiped a god represented on Earth by an awe-inspiring drum. It stood taller than any man. Rubbing the cowhide stretched across its gigantic body, fashioned from a hollowed-out tree trunk, made a sound that could be heard throughout the villages clustered around the Pokomo king’s compound.