Simplify the following text for a Grade 9 native English-speaking person.
Original: The Wiradjuri tribal area has been described as `` the land of the three rivers , the Wambool later known as the Macquarie , the Kalare later known as the Lachlan and the Murrumbidgee ( Murrumbidjeri ) .
Simplified: The Wiradjuri land has been called `` the land of the three rivers , the Wambool ( Macquarie ) , the Kalare ( Lachlan ) and the Murrumbidjeri ( Murrumbidgee ) .