The demonstration began at noon on Saturday in the Welsh capital, Wales Online news portal said. The participants marched through the streets of Cardiff, waving flags and carrying banners that read "Independence."
According to the news outlet, actor Julian Lewis Jones, who plays Boremund Baratheon in the hit HBO series "House of the Dragon," joined the march and addressed its participants.
A similar demonstration took place in the city of Wrexham in north Wales in July and attracted around 8,000 people.