The Tulu are an evil and devious race, demonstrating the canny wickedness of Faustian devils and the perverse pleasures of hentai tentacle pornography.
A portmanteau of the words Architecture and Ecology, arcologies are megastructres that are built with an eye towards environmentally friendliness.
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.