Complex sentence: Large libraries existed in Iran both before and after the advent of Islam and throughout many periods in Iran's history, including the libraries at Gondeshapur, School of Nisibis, and Sarouyeh during the pre-Islamic era of Iran.
Split into simpler sentences: Large libraries existed in Iran both before and after the advent of Islam and throughout many periods in Iran's history. One can mention the libraries at Gondeshapur, School of Nisibis, and Sarouyeh during the pre-Islamic era of Iran.