Sheikh Sabah Al-Sabah, the emir of Kuwait, has died at 91, according to Kuwaiti officials. Known as one of the Middle East’s great conflict mediators, Sabah served as a go-between for Saudi Arabia, the United Arab Emirates, Bahrain, and Qatar in 2014, when the nations feuded with Qatar over accusations it was undermining their power. Born in 1929, Sabah has held government posts since age 25, serving as Kuwait’s foreign minister from 1963 to 2003 when he was promoted to prime minister. In 2006, he unexpectedly became emir when Sheikh Saad Al-Sabah suffered a health crisis nine days into his reign. Countries and leaders throughout the region paid tribute to Sabah, with Jordan declaring 40 days of mourning per CNN. “Today we lost a great brother and a wise leader who loves Jordan,” Jordanian monarch King Abdullah tweeted. “(He) did not hesitate in his benevolent endeavors to make every effort to unite the Arab ranks.”