The rise and fall of the medieval Islamic Empire - Petra Sijpesteijn & Birte Kristiansen

In the 7th century CE, one man started a chain of events that would change the world order for good. The prophet Muhammad united the people of the Arabian Peninsula through the formation of Islam. These people included both nomadic Bedouin tribes and the inhabitants of oasis cities like Mecca and Medina.

Until Muhammad’s time, the region hadn’t been considered a serious match for the powerful neighboring Persian and Byzantine empires. But the alliance Muhammad formed was political as well as religious, an empire with Medina as its political heart and a force to be reckoned with. Muhammad was a one-of-a-kind leader.

He had been a member of the Quraysh, the tribe that controlled Mecca. After Muhammad’s death, those close to him deliberated who should succeed him— a contentious question. Abū Bakr, Muhammad’s father-in-law, emerged victorious and became the new caliph, or successor.

Over the next 30 years, four caliphs, all from Muhammad's tribe, conquered vast areas beyond Arabia, including their mighty neighbors, the Persians and the Byzantines. But as the empire expanded, dissent within it grew and a civil war erupted. The fourth caliph, Ali, was assassinated.

Afterwards, the Umayyad Dynasty came to power. The Umayyads were from the same tribe as Muhammad, but from a different, rival clan. They extended the empire’s reach from present-day Spain to India and made Damascus their capital.

But an empire this vast, full of many different peoples, was at risk of conflict and fracture. The Umayyads stabilized it by replacing the ruling elite in conquered territories with Muslim officials, while largely allowing the day-to-day customs of local populations— including their religious preferences— to continue. Arabic was used as the administrative language, unifying political affairs across the empire, but people continued to speak and write local languages, too.

Still, many in the empire were dissatisfied with Umayyad rule and questioned the dynasty's legitimacy. The Abbasid family capitalized on these sentiments, promoting themselves as more direct descendants of the prophet, though their actual relation to Muhammad was more tenuous than they claimed. They overthrew the Umayyad caliphate in 750 CE, becoming the second great dynasty of the Islamic Empire.

To establish themselves as the new rulers, they relocated the capital once more, this time building a new city: Baghdad. Under Abbasid rule, the elite enjoyed a lifestyle of luxury, thanks to extensive trade networks that brought both products and people from all over the known world to Baghdad. Byzantine, Persian, Indian and Arab cultures and knowledge intermingled, leading to artistic and scientific advancement.

The caliph was wealthy and powerful beyond imagination. But there was never a clear line of succession dictating who would become the next caliph. Any male relative of the former caliph was eligible, so brothers, nephews, and uncles fought to gain power.

Within the court, army officers, wives, concubines, and government officials all demanded their share of the treasury. Because the caliph depended on his entourage to stay in power, each transition of rulership opened the doors for favoritism and corruption. Outside the court, many questioned the legitimacy of the caliph, noting that the caliph’s religious duty to moral excellence was at odds with the court’s decadent displays of wealth.

In 1258 CE, the Mongols approached Baghdad. They encountered little resistance as they thoroughly destroyed the city. Legend has it that they rolled the caliph in a rug and had horses trample him to death, and that the Tigris River ran black from the ink of the manuscripts that were thrown into it.

The siege of Baghdad laid bare a longstanding reality: for centuries, the caliphs had ruled mostly symbolically. Local leaders throughout the empire had grown more powerful, and they refused to pay taxes, spending the money on their own courts instead. The time of one united Islamic Empire was over, but its influence through written and spoken Arabic, Islam, and the ideas of its greatest intellectuals, left a lasting mark on the world.