Sultan Qaboos bin Said of Oman, the longest reigning leader in the Arab world, died Friday at age 79.

The death, announced by the official Oman News Agency, came after an almost 50-year rule and a battle with what was widely believed to be colon cancer. Qaboos left no designated heir, having no known brothers or children, raising the prospect that a cousin will try to replace him in a possibly contentious succession process.

Born in 1940, Qaboos took power in a coup against his father in 1970 at the young age of 29.

ADVERTISEMENT

Qaboos is widely credited with implementing a litany of reforms in Oman, transforming a nation torn by civil war into a stable, oil-exporting country strategically located in the Persian Gulf that was able to make peace with neighbors.

Under the sultan's rule, Oman became the first Gulf country to create trade ties with Israel and maintain peaceful ties with the U.S., Saudi Arabia and Iran, despite the three countries’ dueling interests.

Qaboos molded a role for himself as a regional mediator, sponsoring peace talks between Iran and Iraq in the 1980s and hosting discussions that led to the landmark nuclear deal between Washington and Tehran in 2015.

“We do not have any conflicts and we do not put fuel on the fire when our opinion does not agree with someone,” Qaboos told a Kuwaiti newspaper in a 2008 interview.

He also oversaw reforms at home that outpaced those of several of Oman’s Gulf neighbors, such as giving women the right to vote in the 1990s and allowing them for run for public office.

However, the later years of his rule were marked by frustrations over quiet crackdowns on activists and the media and complaints over government corruption. Oman was rocked by protests in 2011 during the Arab Spring, the first demonstrations the country had seen in decades.