Original: The peninsula comprises the Mexican states of Yucatán, Campeche, and Quintana Roo; the northern part of the nation of Belize; and Guatemala's northern department of El Petén.
Simplified: The peninsula is covers up the Mexican states of Yucatán, Campeche, and Quintana Roo; the northern part of Belize; and Guatemala's northern department of El Petén.