Complex sentence: In 472, Gaero, the ruler of Baekje, sent a letter to the emperor of Northern Wei, stating that he was having trouble interacting with him due to frequent Goguryeo intervention, thus calling for military action against Goguryeo.
Split into simpler sentences: In 472, King Gaero of Baekje sent a letter to the emperor of Northern Wei. He stated that he was having trouble interacting with Wei because of frequent Goguryeo intervention, thus calling for military action against Goguryeo.