Simplify the following text for a Grade 11 native English-speaking person.
Original: Bordered on the south by the state of Victoria and on the east by the Great Dividing Range , the Riverina covers those areas of New South Wales in the Murray and Murrumbidgee drainage zones to their confluence in the west .
Simplified: With the state of Victoria to the south , and the mountains of the Great Dividing Range to the east , the Riverina covers those areas of New South Wales in the Murray and Murrumbidgee river systems .