RIYADH, Saudi Arabia (AP) - As Saudi Arabia mourned its late ruler, King Salman bin Abdul-Aziz Al Saud quickly set the course for the monarchy's future Friday by naming a second-in-line to the throne from the next generation of princes for the first time. The appointment came as the ultraconservative Sunni-ruled kingdom buried King Abdullah after a subdued and austere funeral attended by Muslim dignitaries from around the world. Abdullah, who led the country for nearly two decades, died early Friday at the age of 90 after falling ill with pneumonia. Buried that same afternoon in an unmarked grave, Abdullah's body was shrouded in a simple beige cloth, his remains interred without a coffin in line with Islamic tradition that all people - even kings - are equal in death before God. Just hours before, the ruling family once again showed its shrewd ability to coalesce quickly around thorny issues of succession. A royal decree affirmed Salman's half brother Muqrin, 69, as Crown Prince and the king's immediate successor. Salman named Prince Mohammed bin Nayef, 55, as deputy crown prince. It marked the first time a grandson of Saudi Arabia's founder, King Abdul-Aziz Al Saud, is in line to become king. King Salman, 79, promised in a nationally televised speech to continue the policies of his predecessors. "We will continue adhering to the correct policies which Saudi Arabia has followed since its establishment," said Salman, a veteran of the country's top leadership who served for nearly 50 years as the governor of the capital, Riyadh, and later as defense minister. Salman likely will avoid directly challenging the kingdom's influential clerics and is not expected to usher in sweeping political reforms or rapidly expand women's rights, in line with previous monarchs. For almost a century, Saudi kings have overseen Mecca, giving them enormous prestige and global clout with the world's 1.6 billion Muslims. To reemphasize their claim to Islam's holiest sites, the current King Salman, like the two kings before him, assumed the title of "Custodian of the Two Holy Mosques," a reference to Mecca's Grand Mosque and the Prophet Muhammad's first mosque in Medina. For more than six decades, power has passed among the sons of the country's founder, from brother to brother. But the ranks of that generation, largely in their 70s and 80s, are thinning. The decision to name Mohammed as deputy crown prince helps alleviate uncertainty over which of the late King Abdul-Aziz's hundreds of grandsons would ascend to the throne. Mohammed is the son of Salman's full brother, Nayef, who was a formidable power in Saudi Arabia until his death in 2012. Mohammed, who oversees Saudi counterterrorism efforts, will keep his post as interior minister. He was the target of a botched assassination attempt by al-Qaida militants in 2009. A leaked U.S. diplomatic cable from that same year described him as "more rounded, more intellectual (and) more educated" than his father, who was interior minister and crown prince before him. The Saudi Embassy in Washington says Mohammed graduated with a political science degree from Lewis and Clark College in Portland, Oregon. Salman also appointed his son, Prince Mohammed, as defense minister. The prince, in his 30s, studied law in Saudi Arabia. He was head of his father's royal court when Salman was crown prince and is among his most-favored sons. Friday afternoon, state television aired images of prayers for King Abdullah. He was buried in Riyad's al-Oud cemetery. Hundreds gathered outside the cemetery, which was guarded by security officials. One billboard in the capital with Abdullah's image said: "To God we belong and to God we shall return." Abdullah officially ascended to the throne in 2005, but had been de-facto ruler for around a decade before that. Fahad Nazer, a Saudi political analyst, said Abdullah often spoke to Saudis like he was "just another citizen." "'I am one of you' was a favorite line of his," Nazer said. U.S. President Barack Obama described the late king as a candid leader who believed in the importance of the U.S.-Saudi relationship. Under his leadership, Saudi Arabia joined the United States and other Arab countries in carrying out airstrikes in Syria against the Islamic State extremist group. In his first speech as king, Salman also made an oblique reference to the chaos gripping the greater Middle East, saying: "The Arab and Islamic nation is in dire need today to be united and maintain solidarity." Abdullah's regional rivals also expressed their condolences. Israeli President Reuven Rivlin described Abdullah as providing "grounded, considered and responsible leadership." Iranian President Hassan Rouhani, the elected leader of Saudi Arabia's Shiite rival, wished the king a "peaceful rest" and success for the country he leaves behind. Turkish President Tayyip Erdogan and the rulers of Qatar, Kuwait and Bahrain were among those who took part in the Muslim-only funeral. Western diplomats and other leaders are expected to visit Saudi Arabia in the coming days to offer condolences. Salman takes the helm at a time when the oil powerhouse is trying to navigate social pressures from a burgeoning youth population. Over half of Saudi Arabia's population of 20 million is under 25 and seeking jobs and increasingly testing boundaries of speech on the Internet, where criticism of the royal family is rife. The country also faces plunging global oil prices and multiple threats from its southern border with Yemen and northern border with Iraq. In a departure from past monarchs, Salman used his Twitter account to send a message of hope to his 1.3 million followers. "I ask God to ensure my success to serve our dear people and realize their hopes, and to preserve our nation and society's security and stability, and to protect it from all evil," the message read. Batrawy reported from Dubai, United Arab Emirates.