Zimbabwean President Robert Mugabe celebrated his 93rd birthday on Saturday amid granite hills where ancient spirits are said to dwell, defying calls to resign after nearly four decades in power in a region known for opposing the man who says he'll run again in 2018 elections. Thousands of government supporters, some wearing clothing adorned with Mugabe's image, converged in Matabeleland for a birthday bash and show of strength for the ruling ZANU-PF party, beset by squabbling in the past year as the elderly president weakened and factions, one including his wife Grace, sparred ahead of an expected power vacuum. Mugabe, a former rebel leader who took power after independence from white minority rule in 1980, declared a few days ago that most Zimbabweans think nobody can replace him. The longevity of the world's oldest head of state is a source of heartache for Zimbabwe's splintered opposition and uncertainty for investors, leaving the economically struggling country in limbo. Mugabe on Saturday wore dark glasses and a multi-colored jacket bearing an image of himself in younger days, sitting impassively as speakers praised his leadership and delegates from ruling parties in Botswana, Namibia, Angola and Zambia kneeled at his chair to greet him. The Chinese ambassador read a congratulatory message from President Xi Jinping. At one point Mugabe raised his fist in salute, but he also rested his drooping head on one hand. His wife adjusted his glasses. Much of the president's speech, which lasted more than an hour, was personal. He described his life as a "long, long journey," saying it was difficult to predict how long it would last. "The decision that you continue to live and to enjoy life is that of the one personality we all call the almighty God," he said. His hands gripping the podium, Mugabe spoke slowly. He said that at times he felt alone, but that he has a "mission" and "mandate" as Zimbabwe's leader. He appealed for the ruling party to overcome its divisions. Zimbabwe's challenges include drought and a strike by doctors over working conditions that has forced army and police doctors to deploy in public hospitals. The government has endured other crises, rejecting decades of opposition and Western allegations about human rights violations, voting irregularities and economic mismanagement. Mugabe, who turned 93 on Tuesday, also has been serenaded at a palace cake-cutting by singers who wished him "many more" birthdays. Air Zimbabwe, the cash-strapped national carrier, and other entities took out birthday notices in pro-government media. Dancers and musicians performed ahead of Saturday's party at a school in Matopo Hills, on the outskirts of Bulawayo city with caves and rock art dating back thousands of years. The region, whose mystical-looking rock formations have been the setting for religious ceremonies, is also associated with the often violent fissures of pre- and post-colonial Africa. British colonialist Cecil John Rhodes is buried here. It is also the site of mass graves of some of the thousands of Ndebele people killed in the 1980s by a North Korea-trained military unit loyal to Mugabe, a member of the rival Shona ethnic group. The memory of that episode prompted some anti-government activists to denounce the selection of Matopo Hills for Mugabe's birthday party, though ruling party figures said it will promote tourism in the area. Mugabe's state security minister at the time of the killings, Emmerson Mnangagwa, is now a vice president and possible successor. Some ruling party members who support him have criticized Grace Mugabe, a leader in a rival faction who recently said her husband should run as a "corpse" if he dies before the next elections. Mnangagwa is also sticking to the official script that Mugabe is the only option for now, denouncing any "mad young people" in the ZANU-PF party who want him to oust Mugabe. The ruling party, Mnangagwa said, "will rule forever" and will vote for Mugabe in next year's elections. — AP