Pictograph of two people standing back-to-back. Based on the original meaning "back", now written as 背. The current meaning "north" is a phonetic loan.

Evolution

Oracle script

(~1250-1000 BC)

Seal script

Mid Western Zhou (~900 BC)

Seal script

Shuowen (~100 AD)

Clerical script

Eastern Han dynasty (25-220 AD)

Regular script

Modern

 More