Saudi Arabia’s Al-Ahsa Oasis was added on Friday to UNESCO’s World Heritage List, the world cultural body said.
Oman’s ancient city of Qalhat was also added.
Saudi Arabia's lush Al-Ahsa oasis is dotted with yet-to-be-excavated archeological sites and carries traces of human occupation dating back to Neolithic times.
Al-Ahsa "was a commercial center for the Hajar territory of Bahrain," reads the Saudi submission to UNESCO.
"Archaeological evidence shows that it exchanged products from southern Arabia and Persia as well as throughout the Arabian Peninsula."
Oman's Qalhat also dates back to pre-Islamic times.
The port city on Oman's Indian Ocean coast was once a key hub for trade in goods including Arabian horses to Chinese porcelain, according to the Omani submission.
The case of Qalhat also demonstrates the power women could hold in Arabian society at the time.
"In the 13th century ... the governor Ayaz split his presence between Hormuz and Qalhat, which in his absence was ruled by his wife Maryam," the submission reads.
"She, Bibi Maryam, is said to have built the Great Friday Mosque and a mausoleum for her late husband. She continued ruling after her husband's death until at least 1319."
The World Heritage designation is a prestigious one for the Gulf states, looking to make their mark as culturally rich tourist destinations.