John II of Castile was a king who ruled from 1406 to 1454. He was born in 1402 and became king at a young age after the death of his father, Henry III of Castile. His reign was marked by political instability and conflicts with the nobility, which often challenged his authority. During his rule, John II sought to strengthen the monarchy and improve the kingdom's finances. He is known for his patronage of the arts and literature, which helped foster a cultural renaissance in Castile. His reign laid the groundwork for future developments in the region.