Saudi Arabia's King Abdullah, who came to power in 2005 as the sixth ruler of the top oil exporter, started cautious reforms as part of his drive to open up the absolute monarchy and create jobs for its growing population.
Abdullah, believed to be aged about 87, went to the United States in November for medical treatment for a blood clot that complicated a slipped spinal disc.
He arrived in Morocco from New York on Saturday for convalesence, state media said.
Saudi Arabia remains an absolute monarchy, so economic and social policies depend on who is leading the country. Interior Minister Prince Nayef bin Abdul-Aziz is considered to be in a strong position to assume the leadership if serious health problems afflict the king and the crown prince.
The Al-Saud family rules in alliance with clerics who apply an austere version of Sunni Islam, exercising control through mosques, the judiciary and education, and with their own police.
Some of Abdullah's social, education, judiciary and economic reforms were resisted by conservative clerics who objected to loosening social controls.
Analysts and diplomats say the economic reforms will not be affected if the king dies, but the social openings he has made may take longer to bear fruit.
Here are some of King Abdullah's main reforms:
King Abdullah launched a plan to overhaul the state education system, spending over $2.4 billion, but changes to school curriculums have been minimal as resistance from the religious establishment slowed down the pace of reform.
In Saudi Arabia the state education system is dominated by Islamic teachings and any changes to make it more modern or cut religious content faces opposition from clerics.
The king's campaign to totally overhaul the Saudi textbooks to remove chapters which promote bigotry and religious fanaticism against Christians, Jews and Shi'ites was met with strong resistance.
He did manage to introduce some modifications to cut "intolerant and offensive" language.
Before the Sept. 11 attacks on New York and Washington in 2001, little attention was paid to the outpouring of religious fanaticism from Saudi Arabia's schools and mosques.
But when it emerged that 15 of the 19 hijackers were young Saudis, questions arose about the extent to which an educational system under the control of the powerful religious establishment was instilling bigotry and hatred of the West in its young people.
King Abdullah removed the head of the supreme court, a hardline cleric, as part of his efforts to modernise the court system in 2009. He also set up appeals and commercial courts but diplomats say the pace of judiciary reform is still slow.
In Saudi Arabia there is still no consistent law application as courts in different provinces hand out different verdicts for the same crime.
Abdullah was blunt in describing the economic challenges that lay ahead for Saudi Arabia.
Saudi Arabia is spending $400 billion over the five years to 2013 to upgrade its infrastructure and create more jobs for its population of over 18 million. The king has also launched a plan to build five economic and industrial cities that aim to diversify the economy and create more jobs.
But his attempt to attract more foreign investment has been hampered by a debt crisis involving family firms seeking the restructuring of billion of dollars of debt.
The king has also allowed limited ownership of shares to foreigners into the Arab world's largest bourse.
Despite his efforts to lower oil dependence, the oil sector still contributed to 24 percent of GDP in constant prices in 2009, compared with 29 percent in 2005 when he took the throne.
In February 2009, King Abdullah removed two radical clerics from senior positions and appointed the first female as a deputy in the education ministry.
He launched a national dialogue under his auspices to brainstorm challenges facing the kingdom but diplomats say it has done little for the Shi'ite minority that still complains of discrimination in state jobs and limited religious freedoms.
(Compiled by Asma Alsharif; Editing by Samia Nakhoul and Noah Barkin)