The Mongols enter the peninsula ostensibly to rid it of the Khitan. It's a brief honeymoon period until the Mongols force Goryeo into its suzerainty. The relationship rapidly deteriorates from there. It’s a short period in time, just 16 years from 1218-1231, but it’s chock full of geopolitics. Not so much battle scenes, which is in the next episode, but plenty of diplomatic intrigue and a little spy craft thrown in. I’m excited, and I know you are, too.