Simplify the following text for a Grade 8 native English-speaking person.
Original: The lake 's importance declined when the Byzantines lost control and the area came under the control of the Umayyad Caliphate and subsequent Islamic empires .
Simplified: The lake lost importance when the Byzantines lost control of it . The area came under the control of the Umayyad Caliphate and later Islamic empires .