“Every crafter has colleagues in mind and art is lesser or better skilled, so they watch each other. Both to learn and correct flaws. Constantly raising their standard, thus was born the idea of Guilds their ranks and council.”
They were spawning forth prior to the Hordes emerging. And grew from being bullied by the Nobility to powerful organisations. Each fully capable of withstand pressure and unjust taxing, but united Guilds realised they overmatched tax-laying opponents.