The Principality of Wales exists between 1216 and 1536, encompassing two-thirds of modern Wales during its height between 1267–1277.

For most of its history it is "annexed and united" to the English Crown.

However, for a few generations, specifically the period from its foundation in 1216 to Edward I's completion of the conquest of Wales in 1284, it is de facto independent under a Welsh Prince of Wales, albeit one who sweras fealty to the King of England.The Principality is formally founded in 1216 at the Council of Aberdyfi and later recognized by the 1218 Treaty of Worcester between Llywelyn the Great of Wales and Henry III of England The treaty gives substance to the political reality of thirteenth century Wales and England, and the relationship of the former with the Angevin Empire.

The principality retainsa great degree of autonomy, characterized by a separate legal jurisprudence based on the well established laws of Cyfraith Hywel, and by the increasingly sophisticated court of the House of Aberffraw.

Although it owes fealty to the Angevin king of England, the principality is de facto independent, with a similar status in the empire to the Kingdom of Scotland.

Its existence has been seen as proof that all the elements necessary for the growth of Welsh statehood were in place.

The period of de facto independence ends with Edward I's conquest of the Principality between 1277 and 1283.

Under the Statute of Rhuddlan the Principality loses its independence and becomes effectively an annexed territory of the English crown.

From 1301, the crown's lands in north and west Wales form part of the appanage of England's heir apparent, with the title "Prince of Wales".

On accession of the Prince to the English throne, the lands and title become merged with the Crown again.

On two occasions Welsh claimants to the title rise up in rebellion during this period, although neither ultimately succeeds.