 Makkah was never the capital of any of the Islamic states.Muslim rulers did contribute to its upkeep, such as during the reigns of 'Umar (r. 634–644 CE) and 'Uthman ibn Affan (r. 644–656 CE) when concerns of flooding caused the caliphs to bring in Christian engineers to build barrages in the low-lying quarters and construct dykes and embankments to protect the area round the Kaaba.Muhammad's return to Madinah shifted the focus away from Makkah and later even further away when 'Ali, the fourth caliph, took power chose Kufa as his capital.