The full name of the Oman Region is the Sultanate of Muscat and Oman, which was once a country spanning two continents.
During the reign of the previous Sultan, Said bin Sultan, the Sultanate of Muscat and Oman occupied vast lands, encompassing not only the territories of present-day Oman but also parts of the United Arab Emirates and Pakistan Gwadar.
Of course, this also included Oman's East African Territory, which is why it was said that Oman was once a country spanning two continents.
However, after the old Sultan's death, his two sons inherited the mainland of Oman and the East African Territory respectively, leading to their split.
The current Sultanate of Muscat and Oman only governs the mainland of present-day Oman, with all other lands belonging to other countries.
Spain's colonial target was also just the mainland of Oman; even if Oman still controlled the East African Territory at this time, Carlo wouldn't be bothered with any extra thoughts.
