Monarchs of the Kalmar union were all cognatic descendants of the House of Mecklenburg.

Entity and relation annotations:
id: 0
type: entity
value: text: the Kalmar union
labels: <Organization>
id: 1
type: entity
value: text: the House of Mecklenburg
labels: <Organization>
id: 2
type: entity
value: text: Monarchs of the Kalmar union
labels: <Organization>
type: relation
to_id: 0
labels: Organization:is_subordinate_to:Organization
from_id: 2