How did Islamic civilization spread to encompass such an extensive empire?

Answer 1

It's unclear from the question what "Islamic Civilization" is or the "Muslim Empire" is.

As for Muslim Empire, there have been hundreds of different "Muslim Empires" ranging from the Rashidun Caliphate, to the Taifa Spanish Caliphates, to the Berber Almoravids and Almohads, to the Shiite Egyptian Fatimids, the various Turkish Muslim Empires (Seljuks, Ottomans, Timurids, Mughals), the Indonesian Achenese Sultanate, the Omani Sultanate that extended along the East African coast, etc.

As for Islamic Civilization, does that refer exclusively to the various Islamic Empires? Does that refer to cultural traditions of Muslims regardless of who's in power? Does that refer to the construction of the Islamic religion itself (i.e. the presence and power of Qadis, Faqihs, Ayatollahs, Imams, Mullahs, etc.)? Does that refer to traditional Muslim world-views and ethical stances?

When these definitions and questions are so nebulous, it is impossible to answer the question any more specifically than to say the following:

Islamic civilization did not necessarily continue to flourish without an Islamic Empire. There were cases where it did and there were others where it languished or collapsed. In those cases where it flourished, it did so because it was more entrenched than the controlling power. The reverse occurred when the controlling power was able to uproot the traditional culture.

Answer 2

Muslim rulers built cities where schoolars and artists made advances in many fields

Answer 3

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