Beginning with the creation of the Welsh–Scottish League in 1999, the league became known as the Celtic League when it grew to include teams from Ireland, Scotland and Wales. The league was sponsored by Irish cider makers Magners from the 2006–07 season until 2010–11. At the start of the 2010–11 season, the league expanded from 10 to 12 teams, adding two Italian teams. Following the end of Magners' sponsorship, the league was sponsored by RaboDirect from 2011–12 through to 2013–14. The Pro12 name was adopted in 2011 to reflect that the league now included teams from outside the Celtic nations. A further expansion to 14 teams (and the subsequent renaming to Pro14) took place from the 2017–18 season, with two South African teams joining the Championship until the 2019–20 season. The recent sponsorship deal with Guinness began at the beginning of the 2014–15 season, and concluded after the Pro14 Rainbow Cup in July 2021. Following the rebranding to the United Rugby Championship, the league formed a new partnership with Roc Nation.