Short answers, pulled from the story.
In 410, the Roman province of Britannia covered the area that is now England and Wales as a single administrative unit. The Romans administered this region together until their departure from the land.
The Laws in Wales Acts 1535 and 1542 formally incorporated Welsh territories into the English legal system. These acts consolidated administration of all Welsh territories under the Kingdom of England.
Parliament passed the Wales and Berwick Act 1746 to clarify whether references to England included Wales in legislation. Before 1746 it was unclear if laws mentioning England applied to Wales.
A referendum on the 3rd of March 2011 granted the National Assembly for Wales created in 1999 direct law-making powers. This event marked the first time in almost 500 years that Wales had independent legislative authority.
The Government of Wales Act 2006 allowed the Senedd to pass its own laws without consulting Westminster. Each piece of Welsh legislation is known as an Act of Senedd Cymru.