Simplify the following text for a Grade 8 native English-speaking person.
Original: The tomb of Prophet Muhammad later became part of the mosque when it was expanded by the Umayyad Caliph Al-Walid I. Mount Uhud is a mountain north of Medina which was the site of the second battle between Muslim and Meccan forces .
Simplified: The tomb later became part of the mosque when it was expanded by the Umayyad Caliph Al-Walid I. The first mosque of Islam is also located in Medina .