Dragon is associated with a negative force whitch hold you back.and never let you go past that.

when you try to do something biggger or anything ,there is a counter force which hold you back.

Don’t fear ,just go through,
The cave you fear to enter,holds the treasure you seek.

Dragon is symbolze a thresold gardian in the context of chinese locally ,geographical confitioned.

it will change geographically.

Like in india.
it symbolize by a VERY aggressive rakchhas.