Gede, which reached its peak in the 15th century, was inexplicably abandoned in the 17th or 18th century. Some theories point to disease and famine, others blame guerrilla attacks by Somalian Galla people and cannibalistic Zimba from near Malawi, or punitive expeditions from Mombasa. Or Gede ran out of water – at some stage the water table here dropped rapidly and the 40m-deep wells dried up.