Time is talked about, and therefore thought about, differently depending on your language family. Not only Aymara in the Andes, but Biblical Hebrew, also "face" the past and "back" the future. Also in Biblical Hebrew, your primary compass point isn't North, but East. So "right hand" equals South and "left hand" equals North. As the Sun moves across the sky you can see how in facing sunrise, Biblical Hebrew faces the past, and with your back to the sunset, the opposite regarding the future.