The King Loves, set in Goryeo in the late 13th century, premiers this week. As with any historical drama, it's helpful to know some facts to make better sense of the story. Here are some sources of information from Week 1, Episodes 1-4, that may help.
From DramaLoveAddicts: A Beginner's Guide to Sageuk Vocabulary
From Lilac Reel: Essential Words to Know
From Soompi: Character Relationship Chart
History of Gangwong-do: Lee Seung-hyu (pen name Dongangeosa)
About Falcronry: The Modern Apprentice
Spoiler Alert! From Six Flying Dragons: Historical Background for The King Loves
From Instagram: Another Character Relationship Chart