Under the Umayyads the Caliphate grew rapidly geographically. Islamic rule expanded westward across North Africa and into Hispania and eastward through Persia and ultimately to Sindh and Punjab in modern-day Pakistan. This made it one of the largest unitary states in history and one of the few states to ever extend direct rule over three continents (Africa, Europe, and Asia). Although not ruling all of the Sahara, homage was paid to the Caliph by Saharan Africa usually via various nomad Berber tribes.