Event
Ten thousand years ago the plane of Ravnica boasted untold violence and brutality, with various factions constantly waging war against one or more of the others. Realizing that this neverending war would ultimately destroy everything, a council between ten factions was held, where the leader Azor I suggested establishing a living, breathing enchantment that would end the violence and ensure the survival of the factions. While some of the order-phobic factions had initial disagreements, the other nine leaders eventually concurred that such a pact was the best chance of survival. Each of the ten factions signed the Guildpact, and over time, these factions became the ten guilds of Ravnica.
The power of the Guildpact was subtle; it prevented any guild from dabbling into the business of any other guild or disturbing the stable power balance among the ten by twisting circumstance and coincidence to nullify the disruptive guild's actions. While the Guildpact was credited with bringing relative peace and prosperity to the plane, sporadic clashes between guilds still occurred. Despite any conflicts between the guilds at a particular time though, the anniversary of the Guildpact's signing was celebrated every year with a day-long festival, where all the people laid down their weapons and made merry. This celebration was called The Festival of the Guildpact.
Not all of Ravnica's citizens are a member of a guild; about half of the population is guildless. However, the guilds are a required part of daily life, and their presence is felt everywhere on Ravnica.