Oman is a country on the Arabian Sea in the southeastern part of the Arabian Peninsula. With a population of 3.5 million, Oman is a small nation. Muscat, Oman's capital, was established in 1449 and has been continuously inhabited ever since. Omanians speak a variety of languages, but Arabic is the most widely spoken.

regions that begin with "O"
Other Oceania region names that begin with "O" Oceania is made up of four distinct geographical regions: Micronesia, Polynesia, Australasia, and Melanesia As of 2021, it is anticipated that Oceania will have a population of approximately 44.5 million people and a total area of 8,525,989 square kilometers.
Okinawa
The island of Okinawa in Japan is located in the East China Sea. The rebuilt palace of the Ryukyu Kingdom is in Naha city's Shuri Castle. One of the Gusuku-era Ryukyuan fortresses still standing on Okinawa is the ornate gate of Shureimon. Fine art is on display as well as exhibits on Okinawa's natural and cultural heritage at the Okinawa Prefectural Museum.
Oklahoma
Oklahoma is a state in the US Policy System's South Central Region. It is bounded by Texas to the south and west, Kansas to the north, Missouri to the northeast, Arkansas to the east, New Mexico to the west, Colorado to the northwest, and Arkansas to the east.
Ohio
Ohio is a singular state, best known as the Buckeye State, the Birthplace of Aviation, and the Heart of It All. Cedar Point, the Rock and Roll Hall of Fame, and the Pro Football Hall of Fame are among Ohio's most popular tourist attractions. Spend a day in the great outdoors at Hocking Hills. Ohio's most important inventions are Superman, the phonograph, automobiles powered by gas, golf balls, and the phonograph.

About Oman
The Only Country with the Initial O Oman is a Middle Eastern nation with a long and illustrious history. Its borders are the Gulf of Oman and the Arabian Sea. It is believed that the name of the tribe that settled in Oman gave rise to the name Oman. Oman was a significant trading hub beginning in 2000 BC.
It was a part of Greece for seven centuries before it was taken over by Arabs between 673 and 676 A.D., when Mohammed sent his brother-in-law Ali bin Abi Talib on an expedition against them. After that, when Mohammed sent his brother-in-law on an expedition against them, it became part of Islam.
In 1508, Vasco da Gama led a Portuguese colonization fleet to Muscat, where the local tribespeople resisted conversion or conquest with ferocity. They returned to Lisbon with just one survivor and a few trade goods that they had obtained through extortion tactics after their failed attempt to attain fame and fortune. This included killing anyone who refused to voluntarily give up their wealth after being threatened with death!e
In 1508, Vasco da Gama led a Portuguese colonization fleet to Muscat, where the local tribespeople resisted conversion or conquest with ferocity. They returned to Lisbon with just one survivor and a few trade goods that they had obtained through extortion tactics after their failed attempt to attain fame and fortune. This included killing anyone who refused to voluntarily give up their wealth after being threatened with death!
Credits: https://www.edgeoftheglobe.com/2022/10/10/the-only-country-that-starts-with-o/