Complex sentence: Northern Transylvania is a region of Transylvania, situated within the territory of Romania, that during World War II, as a consequence of the territorial agreement known as the Second Vienna Award, became part of Hungary.
Split into simpler sentences: Northern Transylvania is a region of Transylvania, situated within the territory of Romania. During World War II, as a consequence of the territorial agreement known as the Second Vienna Award, the area was part of Hungary.