Two explanations came to my mind: 1. East - the direction where the Sun appears - was located on the right because the right hand had a special meaning for peop

Two explanations came to my mind: 1. East - the direction where the Sun appears - was located on the right because the right hand had a special meaning for people. 2. South was located down (behind the back of someone reading the map) to provide the maximum amount of light to the reader.