To dream of the direction left symbolises the subconscious and your repressed thoughts/emotions. It is an indication of passivity.
To dream that you are left behind represents feelings of rejection or not fitting into a group. It may also highlight fears of not being able to keep up. You are questioning your abilities. The dream may be telling you that you are not utilizing your full potential. If you left something or someone behind, then it indicates that you are ready to let go of the past or move forward.