The Rise of Islam: From One Man in a Cave to the World's Largest Empire

Most of us learned history like this: Ancient Greece, then Rome, then the Dark Ages, then Europe woke up during the Renaissance. Islam? Barely mentioned, maybe in the context of wars.

But here's the thing. For about 1,000 years, the Islamic world was the most powerful and advanced civilization on Earth. The modern world we live in, with its science, hospitals, universities, and mathematics, owes a huge debt to the Islamic Golden Age. Most people just don't know this because it's rarely taught.

Let's fix that.

Basic Facts About Islam

Islam is the world's second largest religion. Christianity has about 2.3 billion followers. Islam has about 1.8 to 1.9 billion followers. The biggest Muslim country in the world is actually Indonesia, not Saudi Arabia, not Iran.

Islam splits into two main groups:

Sunni: the larger group, found everywhere in the world
Shia: mostly in Iran

The only real difference between them: Shia Muslims believe the leader of Islam must be a blood relative of Muhammad's family. Sunni Muslims don't believe this. Everything else, the Quran, the five pillars, the core beliefs, is the same.

The word Muslim simply means "someone who submits to God."

Who Was Muhammad?

Muhammad was a trader living in the city of Mecca, in what is now Saudi Arabia. He was 40 years old when his life changed forever.

He went to a cave to pray and think quietly. According to Islamic belief, the angel Gabriel came to him there and showed him visions from God. Muhammad memorized everything he saw and heard. Later, these were written down and became the Quran, the holy book of Islam.

Muhammad felt his job was to share God's message with the people of Arabia, who at the time worshipped many different gods. When he started preaching in Mecca, people didn't like it. He was challenging the old way of doing things. Eventually, he was forced to leave.

He traveled to the city of Medina. This journey is called the Hijrah and it marks the starting point of the Islamic calendar.

In Medina, Muhammad became a leader and helped different groups stop fighting each other. Pagans (people who worshipped many gods), Muslims, and Jews all lived there. He created an agreement called the Constitution of Medina that gave everyone the right to follow their own religion in peace.

From day one, Islam was meant to be open and welcoming to everyone. This wasn't just talk. It was written into the founding document.

The Five Pillars: What Every Muslim Must Do

ExpandMillions of Muslim pilgrims gathered at Mecca during the annual Hajj

Islam is very clear about what you have to do to be a good Muslim. There are five basic duties, called the Five Pillars of Islam:

Shahada: Say and believe: there is only one God, and Muhammad is his messenger
Salat: Pray five times every day, facing the direction of Mecca
Zakat: Give some of your money to help the poor
Sawm: Don't eat or drink from sunrise to sunset during the holy month of Ramadan
Hajj: Travel to Mecca at least once in your life for the big annual gathering

The Hajj is one of the biggest gatherings of human beings on the planet. Millions of Muslims go every year. Poor Muslims often save money their whole lives just to make this trip once. That tells you how serious Muslims are about their faith.

How Islam Spread So Fast

ExpandMap showing the rapid spread of Islam — from Muhammad's era (622 CE) through the Rashidun and Umayyad Caliphates to 750 CE

Within less than 100 years of Muhammad's first vision, Islam had spread from a small desert region all the way across the Middle East, North Africa, and parts of Europe and Asia.

The Umayyad Caliphate (around 700 CE) was, by size, the largest empire in the world, bigger even than China, which was also very powerful at the time.

Think about that. Arabia was the poorest, most marginal region in the Middle East. No natural resources. Not a great location. And yet from there, the Muslims:

Completely defeated the powerful Persian Empire
Took half of the Byzantine Empire (the old Roman Empire in the East)
Captured Jerusalem and built the Al-Aqsa Mosque there
Tried twice to take Constantinople (the Byzantine capital), but failed because of its massive walls and a weapon called Greek fire, a liquid that burns even on water

The speed of this is hard to believe. What gave them this power? Not money or weapons. It was an idea, and a very united, motivated group of people behind it.

Three Historical Puzzles

Before we get to the Golden Age, there are three questions that historians still argue about. Nobody has a perfect answer, but the guesses are interesting.

Puzzle 1: Why Are There No Written Records from the First 100 Years?

We know that early Muslims included literate Jews and Christians who knew how to read and write. But we have almost no written documents from the first century of Islam. For something this important, that's very strange.

The most likely reason: politics. The early Islamic movement was a revolution. It was turning the old power structure upside down. Once the Muslims gained power, their leaders didn't want people reading about the messy, rebellious beginnings. It's easier to rule when your history looks clean and orderly.

Also, the people who were personally close to Muhammad, the original followers, were likely pushed out of power over time. Once they were removed, their version of history was removed too.

Puzzle 2: Why Didn't Muhammad Choose a Successor?

Not choosing a successor caused the Sunni-Shia split, which still divides Muslims today. So why didn't Muhammad just name someone to take over after him?

Here's one theory: Muhammad believed the world was about to end. In 622 CE, all three big religions, Jewish, Christian, and the new Muslim movement, believed they were living in the final days before God arrived to bring history to a close. The Persians and Byzantines were at war, which matched the ancient prophecies about a final battle between good and evil.

If God is coming tomorrow, why do you need to plan for next year's leadership? Muhammad may have genuinely believed there wouldn't be a "next year" for human civilization.

Puzzle 3: Why Did Muslims Build Their Mosque on Top of the Jewish Holy Site?

In Jerusalem, the Al-Aqsa Mosque, Islam's third holiest place, sits directly on top of the Temple Mount, which is the holiest place in Judaism. The Romans had destroyed the Jewish temple there in 70 CE. Jews desperately wanted to rebuild it.

If Islam was supposed to be tolerant of Jews, why build a mosque right on top of their most sacred ground?

One theory (and this is just a theory): the mosque was originally meant to be the Jewish temple. When Jewish people helped the early Muslims take Jerusalem, the deal may have been that the Muslims would let the Jews rebuild their temple there. But over time, as politics changed, that promise was quietly abandoned and the temple became a mosque instead.

This is still a very sensitive issue today. Some Jewish groups want to rebuild the temple, but that would mean removing or destroying the mosque. It's one of the most complicated religious disputes in the world.