There were a number of small independent buffer States between Rome and Parthia and several of them were of Arab tribes. (religion-online.org)
Bolivia, Paraguay, and Uruguay are called buffer states between Brazil and Argentina. (businessinsider.com)
These events vindicated the long tradition of Crown - Aboriginal alliances, from the Covenant Chain to the Royal Proclamation to the plan to establish an Aboriginal buffer state. (thecanadianencyclopedia.com)