Upon the death of Charles V, Castile and Leon were inherited by his ilegitimate son John, together with the Low Countries. The territories were regented by Charles son Philip.
John III of Castile and I of the Low Countries, married Mary I of Scots, in 1566.
This personal union between Castile, the Low Countries, and Scotland remained for almost a century, until King John IV of Castile and II of Low Countries converted to Puritamism in 1662, being forced to abdicate as Castilian king, to his brother Charles.
In 1903, King Alfonso XIII was deposed by a military coup, and a junta asumed the government in Castile, soon followed by the Dictarship of Rivera.
Since 1980, Castile was transformed in a parliamentarist republic with a functional democracy.