Why there are Rangers and Celtic ends at Hampden as age old tradition explained

dailyrecord.co.uk:

Dave Cormack has made no secret of his desire to help change Scottish football for the better since becoming Aberdeen chairman but has often come up against senior figures set in their ways.And the Dons supremo again found himself up against the traditionalists as he failed to change a bit of Hampden history for the Viaplay Cup final – by challenging the SPFL to ‘draw’ Rangers for what has become known as their end of the National Stadium.

The Pittodrie chief is angered by the fact the Red Army won’t be given the opportunity to at least try to sell half of Hampden for the December 17 showpiece and he took to social media to say he had failed with another request.

Cormack said: “Just under six weeks ago, Alan Burrows and I requested time to sell half the stadium which we believed was fair for a ‘neutral’ venue.

We don’t sell them … they go to Rangers. Also asked SPFL to draw for the end of the stadium each team gets to no avail. Surely fair requests for any team.”But why are there so-called ‘Rangers’ and ‘Celtic’ ends at Hampden Park?