The Islamic caliphate expanded very quickly under Muhammad SAW and the first three caliphs. In 639 Muawiyah was appointed the Governor of Syria by Umar RA, The rapid Muslim conquest of Syria and Egypt and the consequent Byzantine losses in manpower and territory meant that the Eastern Roman Empire found itself struggling for survival. The Sassanid Dynasty in Persia had already collapsed. The Islamic empire expanded at an unprecedented rate, but there was a cost associated with it. Many desert nomads and some bandits living between current-day Iraq and Saudi Arabia also joined in, not out of commitment to Islam but to share the spoils and benefit from the change in the social order, after the defeat of the Persian Empire.
In 7th century Arabia, the Islamic community was nearly torn apart by a civil war over the assassination of Uthman ibn Affan RA, Upon Uthman's death, Ali RA finally became the khalifah, tensions were rising on how to punish the assassins, which strained tensions between Ali RA and the Umayyads. This gave birth to the first Islamic Civil War.
THE FITNA [BATTLE OF AL JAMAL AND THE BATTLE OF AS-SIFFIN
HUSAYN [RA] AND THE EVENTS OF KARBALA
On one very special day in the streets of Madina, our prophet [SAW] came out and he was wearing a coat made of black wool and then his grandson Hasan [RA] came and he entered that coat of his and then Husayn [RA] came and entered with him and then Fatima [RA] came in and also entered with them and then Ali [RA] also came and he entered that coat with them and the prophet recited [SAW]: Indeed Allah wants to cleanse you from impurities o Ahl Al-Bayt, Oh household of the prophet [SAW] and purify you,
The events of Karbala reflects the collision of the good versus the evil, the virtuous versus the wicked, and the collision of Imam Husayn versus Yazid. Al-Husayn was a revolutionary person, a righteous man, the religious authority, the Imam of the Muslim Ummah.