Complex sentence: The Livonian Crusade refers to the conquest of the territory constituting modern Latvia and Estonia during the pope-sanctioned Northern Crusades: performed mostly by Germans from the Holy Roman Empire and Danes, it ended with the creation of the Terra Mariana and Duchy of Estonia.
Split into simpler sentences: The Livonian Crusade refers to the conquest of the territory constituting modern Latvia and Estonia during the pope-sanctioned Northern Crusades, performed mostly by Germans from the Holy Roman Empire and Danes. It ended with the creation of the Terra Mariana and Duchy of Estonia.