In 755, Abu Muslim was murdered.
Although he had helped the Abbasids to defeat the former Caliphs, the Umayyad dynasty, the ruling Caliph had given the order to kill him, probably because of his increasing popularity among Iranians and non-Muslims.
Many Iranians, who had expected more freedom and more rights from the new rulers, could not believe that their hero was killed by the ruling Caliph whom they had considered a friend of Iran and Iranians.

This incident led to many revolts, mostly by angry Khurramiyyah (Khorram-Dinān) and some Zoroastrians.
This, in turn, forced the Caliphs to use more violence against the Iranian population in order to keep the eastern provinces under control.
The constant revolts did not come to an end in the following decades, and the Iranian population of the Caliphate was constantly being oppressed.

Babak joined the Khurramiyyah (Khorram-Dinān).
The story of joining the Khorrami movement is being told in Waqed's account, in summary, as follows:
Two rich men named Javidhan b. Shahrak (or Shahrak) and Abu 'Emran were then living in the highland around the mountain of Badd and contending for the leadership of the highland's Khorrami inhabitants.
Javidhan, when stuck in the snow on his way back from Zanjān to Badd, had to seek shelter at Balalabad and happened to go into the house of Babak's mother.
Being poor, she could only light a fire for him, while Babak looked after the guest's servants and horses and brought water for them.
Javidhan then sent Babak to buy food, wine, and fodder.
When Babak came back and spoke to Javidhan, he impressed Javidhan with his shrewdness despite his lack of fluency of speech.
Javidhan therefore asked the woman for permission to take her son away to manage his farms and properties, and offered to send her fifty dirhams a month from Babak's salary.
The woman accepted and let Babak go.

Under the direction of his mentor Javidhan, a leader of one of the sects of the Khorramdin, Babak's knowledge of history, geography, and the latest battle tactics strengthened his position as a favorite candidate for commander during the early wars against the Arab occupiers.

Bābak was a highly spiritual person who respected his Zoroastrian heritage.
He made every possible effort to bring Iranians together and also with leaders such as Maziar to form a united front against the Arab Caliph.
According to the medieval historian, Ibn Esfandyar, who composed the book Tarikh-e Tabaristan (History of Tabaristan), Maziar said:
I (Maziyar), Afshin Kheydar son of Kavus, and Babak had made an oath and allegiance that we re-take the government back from the Arabs and transfer the government and the country back to the family of the Khosrows (Sasanians).

However, one of the most dramatic periods in the history of Iran was set under Bābak's leadership between 816–837.
During these most crucial years, they not only fought against the Caliphate, but also for the preservation of Persian language and culture.

After the death of Javidhan, Babak married Javidhan's wife and became the Khorramis' leader, sometime in the year 816–17 during al-Ma'mun's reign.
Babak incited his followers to rise in rebellion against the caliphal regime.
The reports state that Babak called Persians to arms, seized castles and strong points, thereby barring roads to his enemies.
Gradually a large multitude joined him.

According to Vladimir Minorsky, around the 9th–10th century:
The original sedentary population of Azarbayjan consisted of a mass of peasants and at the time of the Arab conquest was compromised under the semi-contemptuous term of Uluj ("non-Arab") – somewhat similar to the raya (*ri’aya) of the Ottoman empire.
 The only arms of this peaceful rustic population were slings, see Tabari, II, 1379–89.
They spoke a number of dialects (Adhari (Old Azeri language), Talishi) of which even now there remains some islets surviving amidst the Turkish speaking population.
 It was this basic population on which Babak leaned in his revolt against the caliphate.

There had long been groups of Khorramis scattered in Isfahan, Adharb
In 755, Abu Muslim was murdered. Although he had helped the Abbasids to defeat the former Caliphs, the Umayyad dynasty, the ruling Caliph had given the order to kill him, probably because of his increasing popularity among Iranians and non-Muslims. Many Iranians, who had expected more freedom and more rights from the new rulers, could not believe that their hero was killed by the ruling Caliph whom they had considered a friend of Iran and Iranians.
This incident led to many revolts, mostly by angry Khurramiyyah (Khorram-Dinān) and some Zoroastrians. This, in turn, forced the Caliphs to use more violence against the Iranian population in order to keep the eastern provinces under control. The constant revolts did not come to an end in the following decades, and the Iranian population of the Caliphate was constantly being oppressed.
Babak joined the Khurramiyyah (Khorram-Dinān). The story of joining the Khorrami movement is being told in Waqed's account, in summary, as follows:
Two rich men named Javidhan b. Shahrak (or Shahrak) and Abu 'Emran were then living in the highland around the mountain of Badd and contending for the leadership of the highland's Khorrami inhabitants. Javidhan, when stuck in the snow on his way back from Zanjān to Badd, had to seek shelter at Balalabad and happened to go into the house of Babak's mother. Being poor, she could only light a fire for him, while Babak looked after the guest's servants and horses and brought water for them. Javidhan then sent Babak to buy food, wine, and fodder. When Babak came back and spoke to Javidhan, he impressed Javidhan with his shrewdness despite his lack of fluency of speech. Javidhan therefore asked the woman for permission to take her son away to manage his farms and properties, and offered to send her fifty dirhams a month from Babak's salary. The woman accepted and let Babak go.
Under the direction of his mentor Javidhan, a leader of one of the sects of the Khorramdin, Babak's knowledge of history, geography, and the latest battle tactics strengthened his position as a favorite candidate for commander during the early wars against the Arab occupiers.
Bābak was a highly spiritual person who respected his Zoroastrian heritage. He made every possible effort to bring Iranians together and also with leaders such as Maziar to form a united front against the Arab Caliph. According to the medieval historian, Ibn Esfandyar, who composed the book Tarikh-e Tabaristan (History of Tabaristan), Maziar said:
I (Maziyar), Afshin Kheydar son of Kavus, and Babak had made an oath and allegiance that we re-take the government back from the Arabs and transfer the government and the country back to the family of the Khosrows (Sasanians).
However, one of the most dramatic periods in the history of Iran was set under Bābak's leadership between 816–837. During these most crucial years, they not only fought against the Caliphate, but also for the preservation of Persian language and culture.
After the death of Javidhan, Babak married Javidhan's wife and became the Khorramis' leader, sometime in the year 816–17 during al-Ma'mun's reign. Babak incited his followers to rise in rebellion against the caliphal regime. The reports state that Babak called Persians to arms, seized castles and strong points, thereby barring roads to his enemies. Gradually a large multitude joined him.
According to Vladimir Minorsky, around the 9th–10th century:
The original sedentary population of Azarbayjan consisted of a mass of peasants and at the time of the Arab conquest was compromised under the semi-contemptuous term of Uluj ("non-Arab") – somewhat similar to the raya (*ri’aya) of the Ottoman empire.  The only arms of this peaceful rustic population were slings, see Tabari, II, 1379–89. They spoke a number of dialects (Adhari (Old Azeri language), Talishi) of which even now there remains some islets surviving amidst the Turkish speaking population.  It was this basic population on which Babak leaned in his revolt against the caliphate.
There had long been groups of Khorramis scattered in Isfahan, Adharb
Babak Khorramdin