Generating headlines around the world, Saudi Arabia and the United Arab Emirates (UAE) were last month invited to join BRICS—an economic and geopolitical bloc comprising Brazil, Russia, India, China, and South Africa. The full impact of their possible accession to the group is unclear. But the development comes amid Emirati and Saudi efforts to diversify their economic and political relationships with other states.

After years of rumors, BRICS—which took shape in its current guise in 2010—extended invites for new members to join at its 15th summit last month. The gathering was held in Johannesburg in South Africa. Alongside the two Gulf Arab states, Argentina, Egypt, Ethiopia, and Iran were also offered to join the...