While we know of countries balkanizing, is there any such thing as lower-level balkanizing? Like, some regions within a province balkanizing, becoming their own province while still staying a part of the same country, a neighborhood within a city leaving the city and becoming its own city, while still remaining part of the country, etc.
Surprised nobody's mentioned Medieval Europe after the fall of the Western Roman Empire. The state apparatus collapsed and landlords filled the power vacuum, turning large Roman provinces into dozens of independent regional powers. Over time this system consolidated into a handful of larger kingdoms but that process took about a thousand years, during which time large powers rose and broke apart over and over again.