sentences:  Through their control of the region's wells, the Garen rulers effectively held a monopoly over their nomadic subjects as they were the only hydraulic empire in Africa during their reign.Large wells made out of limestone were constructed throughout the state, which attracted Somali and Oromo nomads with their livestock.The centralized regulations of the wells made it easier for the nomads to settle disputes by taking their queries to government officials who would act as mediators.