How Arabs Changed Iran's Fate

I have always been wanting to figure out the reasons for which the lizard eating Arab tribes succeeded in conquering the Persian Empire and forcing them to give up their religion and rituals while they had been standing against the more powerful Roman Empire for all those centuries. Well, in fact, the defeat of the Persian Empire had little to do with the Arab armies being too strong. Arabs moved towards Iran with the purpose of popularizing their new religion, Islam and destroying Zoroastriasm. At this time Persia was under the influence of Sassanian royal family whom in a little while became extremely weak. "Ghobad II", had killed all the members of the royal family, hence, there where no strong rulers left to role the Empire, (in a pariod of 3 years 10 rulers gained power and got exterminated).
To introduce to you the reasons for our loss, I will put them in point forms below:

• the disability of the royal family to perform their duty and to keep the Empire toghether as a result of their conflicts.
• the lose of faith in the Mazdiyasma religion since it required people to spend a good part of their days performing the rituals and limiting their behaviours accordingly (one of the rituals was to keep everything clean at all times). These somewhat hard to fallow rituals resulted in people getting tired and look for something different.
• the sensetized population of the Western part of the Empire, ( Semitic race whom lived in todays Iraq).
• the unhuman like treatment of the citizens of the Iranian cities by the invaders (Arabs).

There has been many evidances of the harsh treatment of Persians by Arabs when they conquered their cities. Forexample, in "kazeroun", the birth place of "salman-e-Parsi", the invaders beheaded one thousand non-Muslims everyday! How much do u think the over all population of "kazeroun" was in those days to have 1000 people killed everyday? In "kharazm", they band people from speaking Farsi ordering their soldiers to cut off the tongue of anyone who dared to speak Farsi. That is how people of "Kharazm" stopped speaking their mother tongue and the popular "kharazmi" dialect vanished. This is why in Arabic, Iranian people are called "Ajam", meaning mute!