Complex sentence: The Spanish conquest of Yucatán was the campaign undertaken by the Spanish "conquistadores" against the Late Postclassic Maya states and polities in the Yucatán Peninsula, a vast limestone plain covering south-eastern Mexico, northern Guatemala, and all of Belize.
Split into simpler sentences: The Spanish conquest of Yucatán was the campaign undertaken by the Spanish "conquistadores" against the Late Postclassic Maya states and polities in the Yucatán Peninsula. The peninsula consists of a vast limestone plain bordered that incorporates south-eastern Mexico, northern Guatemala, and all of Belize.