Excerpted... we don't hear about the Gulf state of Oman very often. It sounds like this article says they were the first Arab nation to send a diplomat to Washington DC way back in 1840.
Washington Should Not Forget Oman
by Luke Coffey
Whether it is the civil wars in Syria and Yemen, the fight against ISIS, Iranian aggression or the rift in Gulf relations, there is plenty happening in the Middle East to keep U.S. policymakers busy. However, with all the noise coming from the region, America should not ignore its relationship with the Sultanate of Oman.
....
Both countries have been partners for almost two centuries . The first contact between the United States and Oman was in 1790, but the relationship became formalized in 1833 after both nations signed the Treaty of Amity and Commerce—the first bilateral trade deal between the U.S. and an Arab Gulf state.
In 1840, Oman sent the first diplomat from the Arab world to be accredited to the United States. Oman became regionally important in a military sense for U.S. interests in 1980 when it became the first Gulf state to welcome an American military base.
Read more at: https://nationalinterest.org/blog/middle-east-watch/washington-should-not-forget-oman-27081
