"Some call it 'the Realm of the Builders' - the Ark refers to it as 'Dius Factorsitius Terravae' or 'The Forge of Worlds.' My opinion? Well, I think it's more of a garden, to be honest."
-Author Dreu, van Heinhelm Household Cleric
The size and number of knots in hair, tied around neck, or hanging from belt could signify family, importance, worship, guild affiliations. Being able to translate the meaning of the size and placement of knots can give you a a large understanding of who somebody is.
May be used in a more barbaric society. Where in cities peoples clothes and crests show who they are, barbarians have no need for this so use knots.