The original gang territory? The medieval center of Siena.
Some fascinating information in this article on medieval communes:
Because much of medieval Europe lacked central authority to provide protection, each city had to provide its own protection for citizens both inside the city walls, and outside. Thus towns formed communes, a legal basis for turning the cities into self-governing corporations. Although in most cases the development of communes was connected with that of the cities, there were rural communes, notably in France and England, that were formed to protect the common interests of villagers.
Every town had its own commune and no two communes were alike, but at their heart, communes were sworn allegiances of mutual defense. When a commune was formed, all participating members gathered and swore an oath in a public ceremony, promising to defend each other in times of trouble, and to maintain the peace within the city proper.
What did it mean for a commune member to defend another? If a commune member was attacked outside the city, it was too late to call for help, as it was unlikely anyone would arrive in time. Instead, the commune would promise to exact revenge on the attacker, the threat of revenge being a form of defense. However, if the attacker was a noble, safely ensconced in a castle (as was often the case), the town commune could not muster the forces to attack him directly. Instead they might attack the noble's family, burn his crops, kill his serfs, or destroy his orchards in retribution.
"How do you govern a community?" is an old question. The rise of towns and cities as a counterbalance to aristocratic authority was a major factor behind the Renaissance and, by extension, the modern world. In some ways, the urban rise hasn't stopped; most of humanity now lives in a city.
The medieval commune busts the stereotypical version of medieval history that, if it considers the peasantry at all, considers them mostly as oppressed masses, focusing instead on the culture and fights of the nobility. Turns out that peasants were plenty active in trying to develop ways to make their own lives less dangerous and hurt those that hurt them. Furthermore, they began independently adapting this basic structure once it proved successful elsewhere.
The medieval commune began by addressing the most basic need: physical protection. It then follows to the most basic way of deterrence: revenge. It is revealing that, in such an anarchic environment, peasants and artisans had an extremely no-bullshit idea of what would protect their own independence, and on what principles their rivals operated.
Interesting too to compare the way the word "commune" has changed over the centuries, from a revenge-based structure of expedience to a byword for egalitarian experimentation.
In function, the medieval commune was more like a gang than a utopian social movement, not striving for any higher ideal than "don't fuck with us and let us run our own affairs." Which, for a medieval peasant, was a big deal. Notice that this relied on organized banditry — including the slaughter of serfs — to protect its own independence.
Like a gang or tribe, anything outside its orbit was expendable, and it focused on striking where its enemy was weak.
Of course, the communes didn't stay that communal, because ad-hoc organization is usually a precursor to more formal hierarchy. The Siena commune, one of the most successful, was ruled by an oligarchy of nine local leaders by the late 1200s. In Italy and Switzerland, where communes had the greatest success, they formed the foundation for more structured city-state republics.
Widespread disorder was a major reason for their existence in the first place, and the formation of centralized states both reduced that issue and created standing forces capable of subjugating the more rebellious communes.
Nonetheless, an interesting wrinkle here: contra the modern narrative, the communes were cooperative and competitive, with the threatened destruction of their foes (or their lands) a major reason for their existence. At the same time, their example shows that the most enduring structures start with an effective structure for a basic need and build from there.