This is a must read / watch for those who consistently question regarding Islam, and how it spread, and also ignorantly challenge it. Though Islam and Muslims inherently do not challenge other religions, rather embrace them, through the message of peace, that is Islam.
Islam: Empire of Faith is a documentary series, made in 2000, that details the history of Islam, from the birth of the Islamic Prophet, Muhammad to the Ottoman Empire.
It is narrated by Ben Kingsley. The first episode deals with the life of Muhammad, the second with the early Caliphates, Crusades, and Mongol invasion, and the third with the Ottoman Empire and Safavid dynasty.
Review quoted from IMDB (http://www.imdb.com/user/ur3156293/comments):
Every human with a bit of intelligence combined with objectivity will appreciate what was revealed by this documentary. Watch it and search for the rest if not satisfied. There are some things which are not mentioned in the documentary about Islamic civilization at all. For instance, it does not talk about stars named with Arabic names in the first observatory founded by Muslims. This documentary mostly only sketches the Islamic civilization and it does a very good job with that considering the existence of those ignorant people asking “Do Muslim’s believe in God?”. It is sad but definitely there are lots of people who will benefit a lot from even 10 minutes of this documentary. It was shocking for me to realize the pilgrims’ visits which could be considered as a kind of globalization achieved peacefully so many years ago.