HOW ISLAM SPREAD ,AFTER THE DEATH OF PROPHET MUHAMMED.

After the death of the prophet Muhammad in 633CE, the rulership was transferred to what is called the caliphate. Islamic caliphate started with the emerging of the first four khalifas (caliph ar-rashidun) ,who spread islam to all arab peninsula, their reign was regarded as the best of the caliphate era.
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THE KHALIFAH AR-RASHIDUN

The first of the khalifa, Abubakr as-sideeq who was the friend and one of the dearest companion of prophet Muhammad play a vital role in spreading islam and uniting the Muslim especially Arab after most of them despair, because of the death of the prophet Muhammad. he was usually quoted for his most popular remark he made that"WHOSOEVER WORSHIP MUHAMMAD, MUHAMMAD IS DEAD BUT WHOSOEVER WORSHIP ALLAH, HE IS EVERLASTING AND HE CANNOT DIE". It was during his reign that musaylama(the false prophet) emerged, and the war was wage against him and his army was conquered, the fierce battle that was led by the Khalid ibn waled ended by killing musaylama himself.
The second khalifa, Umar ibn Khattab who was among the loyal companion of the prophet Muhammad, was made as to the new ruler. It was during his time that islam spread more and the Muslim especially Arab showed their teeth and might to the world, he secure all of the Arab peninsulae including some lands of Byzantines, his army defeated the Persians in a fierce battle and also he took the Jerusalem from the crusader and subjugate it to his ruling, also Egypt was taken by his Army led by Amr ibn Al-as.his reign made a great impact in expanding Muslim territories and rulership.
After him, was the third of them Othman ibn Affan and after the death of Othman, Ali the cousin of the prophet became the khalifa and after Ali's death, Arab world faced many crises and civil war that eventually leads to the emerging of the first dynasty or monarchy which is Umayyad Dynasty.

THE UMAYYAD DYNASTY.

The umayyad Dynasty was from the progeny of umayyah family whose first caliph was Muawiyah.
Umayyad Dynasty which was known for its tribalism was narrated that their ruling favors Arab over non-Arab whether they are Muslims or not and these allegations sparked outrage, frustration, and anger of other Arabs and non-Arab Muslims that see this as an action that is against their faith and religion.
After several years there is a rise in opposition and revolution against Umayyad Dynasty which eventually led to there downfall when Abu Abass as-saffah led a war, which is called the Abbasid revolution which eventually led to another caliphate called Abbasid caliphate in 750CE.

THE EMERGENCE OF ABBASID CALIPHATE.
As-saffah taking oaths in kufa

Abbasid was a dynasty from the progeny of Prophet Muhammad's uncle, Abbas ibn Abdul-Muttalib, which revolt against the Umayyad Dynasty after they claimed that they were to be the real successors of prophet Muhammad as they came from his family. Abbasid dynasty defeated the ummayad dynasty in a battle fought in the battle of Zab (750CE)during the reign of ummayad last khalifa, Marwan. on suffering the defeat Marwan escapes to Egypt where he was finally assassinated.
Abbasid caliphate was first seated at Kufa(modern-day Iraq) before it was moved to Baghdad when it was established by caliph Al Mansur, modern-day Iraq.
Right after their victory Abbasid sent their army to central Asia, where they fought against Tang expansion during the battle of talas. Historian debate whether or not the captured Chinese brought papermaking to Abbasid.

 ISLAMIC GOLDEN AGE(750CE-1258CE).

Islamic golden age started in the 8th century and ended in the 14th century at Mongol invasion. Islamic golden age is an age in which there is prosperity in Education, Culture, Economy, and science, it was dated to have begun in the reign of Abbasid caliph Harun al- Rashid who ruled the dominion from 786-809CE by establishing what is called "House of Wisdom" in Baghdad the world's largest city by then. Scholars in religion and polymath from around the world with different cultural backgrounds were obliged to gather and translate all the world classical books into Arabic and Persian.
During this period Muslims place a big emphasis on finding knowledge especially that of religion and science, scholars were invited from parts of the world to share their knowledge in mathematics, astrology, etc with Abbasid court. Also, scholars in the house of wisdom (Bayt Al hikmah) were engineers and architects who contributed to major construction projects, kept an accurate calendar and they were civil servants, they were also medics and consultants.
In the reign of Caliph Al ma'mun the first astronomical observatories were built in Baghdad.

THE DESTRUCTION OF THE ISLAMIC GOLDEN AGE.

On February 13, 1258, Baghdad was besieged and the house of wisdom was destroyed by hulagu khan army, the books from Baghdad libraries were thrown into river Tigris till the ink turn the river into black, over 800,000 people were killed and many scholars were massacred and the city was decapitated and the glory age was destroyed by Mongols invasion