When Was The Koran Written?

The Koran (also spelled Kuran or Qur'an) was written in the 7th century,  based on the teachings of Muhammad
and became the basis of Islam.   It was originally an recited (oral) text, that was written after Mohammad's death in 632.  A standardized version was established in 650.  Islam is a monotheistic religion with derivation from Christianity and Judaism that replaced the region's idol worship of the time.

For a good historical overview, see the PBS video "Islam, Empire of Faith"  It is a scholarly overview without any religious bias.