Simplify the following text for a Grade 10 native English-speaking person.
Original: He succeeded his father Childeric I in 481 as King of the Salian Franks , one of two main groups of Frankish tribes , They were occupying the area west of the lower Rhine at that time , with their center around Tournai and Cambrai along the modern frontier between France and Belgium .
Simplified: The Salian Franks were one of two Frankish tribes who were then occupying the area west of the lower Rhine , with their center in an area known as Toxandria , between the Meuse and Scheldt ( in what is now the Netherlands and Belgium ) . Clovis 's power base was to the southwest of this , around Tournai and Cambrai along the modern frontier between France and Belgium .