Welsh is a Brittonic language, a member of the Insular Celtic branch of the Indo-European language family. It has been spoken in Wales for over 1,500 years, with its origins tracing back to the arrival of Celtic tribes in the region around the 5th century AD.
English is a West Germanic language, descended from the language of Anglo-Saxon settlers who arrived in Britain in the 5th century AD. While it has been spoken in Britain for over 1,500 years, its origins are later than Welsh.
Therefore, Welsh has a longer history in Britain than English.