I recently watched the British film Kes for about the 10th time, which is set is Barnsley, South Yorkshire in the UK. The film was released in 1969 so quite a long time ago now.
Throughout that film you can hear people use words such as 'tha' and 'thee'. I assume 'tha' is their pronunciation of the word 'thou'. It is a hard film to understand even for native English speakers from the UK, let alone non-Brits or non-native speakers because they speak in such broad dialect.
My dad grew up in Yorkshire and he reckons using such words as 'thou', 'thee', 'thy' etc, which are completely antiquated in modern English are still a feature of certain South Yorkshire dialects. And that film shows this very clearly.
But in English as a whole, these words are no longer used outside of certain set expressions such as 'holier than thou'.