Original: Similar events in the houses of Reuss and Schwarzburg led to all of Thuringia becoming a tangle of mini-states from the late 15th Century until the early 20th Century.
Simplified: The nearby royal houses of Reuss and Schwarzburg also divided up their territory, so Thuringia was a tangle of little states, exclaves and enclaves from the late 15th Century until the early 20th Century.