Complex sentence: Goryeo missions to Imperial China were the diplomatic ventures of Kingdom of Goryeo which were intermittently sent in the years 918-1392, representing a significant aspect of the international relations of mutual Goryeon-Chinese contacts and communication.
Split into simpler sentences: Goryeo missions to Imperial China were the diplomatic ventures of Kingdom of Goryeo which were intermittently sent in the years 918-1392. These represent a significant aspect of the international relations of mutual Goryeon-Chinese contacts and communication.