Ruth Plumly Thompson's books identify the king of the Munchkin Country as Cheeriobed.

Entity and relation annotations:
id: 0
type: entity
value: text: Ruth Plumly Thompson
labels: <Person>
id: 1
type: entity
value: text: the Munchkin Country
labels: <Location>
id: 2
type: entity
value: text: Cheeriobed
labels: <Person>
type: relation
to_id: 1
labels: Person:visits:Location
from_id: 2