In what ways did early Muslim empires experience great political successes and failures?

Early Muslim Empires, like the Umayyads (661-750 CE) and Abbasids (750-1258 CE), experienced success in centralizing power in the Middle East, encouraging the spread of their religion as a way of controlling people and building power off of an immense network of merchants and traders that spanned from western Africa to southeast Asia. When the Umayyads came to power in 661, they were tasked with repairing a fractured Middle East after the death of Muhammad and several assassinations that occurred when the Sunni and Shi'a branches of Islam split. Strong political power, religion, and territorial expansion enabled the Umayyad caliphs to gain considerable power, only strengthened by successful trade routes (the trans-Sahara route, the Silk Road, and the Indian Ocean trade network). The Umayyads expanded their empire to the boundaries of Spain and as far east as the old Persian Empire. The Abbasids, who succeeded the Umayyads in 750, capitalized on this centralized power and built up culture instead, experiencing a flowering of Persian arts and literature. This contributed to an amassed power.
One failure these Muslim Empires experienced were in maintaining territory. While the Umayyads built a massive empire that stretched across north Africa, the Abbasids were unable to maintain the borders. Perhaps it was because the Abbasids moved their Empire further East, making the capital at Baghdad (in modern-day Iraq) instead of Damascus (in modern-day Syria) thereby isolating the more distant parts of the empire in favor of more Persian influence. Regardless, dissension led to fracturing. In Egypt, the Fatimid Dynasty took control of the North African territory, and in Spain some remaining Umayyads and Moors took control. While Islamic civilization was flowering, their political power was failing. The Abbasids ultimately fell in 1258 to the Mongols, invading from the Eastern Steppes, when Baghdad was conquered.
We see more Muslim Empires come later in the early modern period: the Ottomans, the Safavids, and the Mughals. The Ottomans became most powerful when the Turk Mehmed II conquered Constantinople, an old Christian city and part of the Byzantine Empire. The Ottomans lasted until WWI when their empire fell to the Young Turks, a group who encouraged a nationalist Turkey (the empire was also disbanded in the Treaty of Versailles). The Safavids, a Shi'a-run Islamic empire, took control of modern-day Iraq and Iran. They had a powerful army of gunpowder troops and engaged in trade, but were sandwiched between the Ottomans and Mughals and ultimately could not expand or maintain the Empire. The Mughals took control of India in the 1500s and ruled it as a Muslim empire. They were successful in creating a balance between Muslims and Hindus, but ultimately the Mughals were supplanted by the British who used their navy to force their way in to India and take over its economy.