Complex sentence: The region is thought to have formed a separate political unitthe so-called "Nitra appanage duchy" until 1108; historian Ján Steinhübel writes that "Nitra was an autonomous duchy, a clear political entity, which laid the territorial and historical foundation of Slovakia".
Split into simpler sentences: The region is thought to have formed a separate political unitthe so-called "Nitra appanage duchy" until 1108. Historian Ján Steinhübel writes that "Nitra was an autonomous duchy, a clear political entity, which laid the territorial and historical foundation of Slovakia".