In his tent in the desert outside the holy city of Mecca, Suleiman Ibrahim still couldn't believe his luck. His wife, sitting nearby, broke down in tears of joy Thursday as he recounted the day they learned they would perform Islam's hajj pilgrimage.

"The whole family started singing and congratulating me," said Ibrahim, a furniture maker from the southern Egyptian city of Sohag who was one of tens of thousands of Egyptians picked in a government lottery to make the pilgrimage.

"Hamdiya cried then, too," the 45-year-old said, nodding to his wife.

Ibrahim was among nearly 3 million Muslims from around the world who massed in tent cities on the outskirts of Mecca on Thursday for the start of the annual hajj. For many, it is a once in a lifetime chance to cleanse their sins in one of the most important rites of Islam.

This year's hajj takes place amid increasing worries across the Islamic world -- over the bloodshed in Iraq, violence in the Palestinian territories and a new war in Somalia.

Amid those crises, tensions have increased between the two main sects of Islam, Sunni and Shia, whose members come together in the five days of hajj rituals centered around Mecca, birthplace of Islam's Prophet Muhammad.

"We will not allow sectarian tensions from any party during the hajj season," Saudi Arabia's interior minister, Prince Nayef bin Abdulaziz, told reporters ahead of the rituals.

The Islamic affairs minister, Sheik Salih bin Abdulaziz, stressed that point Thursday, telling pilgrims: "The pilgrimage is not a place for raising political banners ... or slogans that divide Muslims, whom God has ordered to be unified."

But for most pilgrims the top concern was faith, not politics.

On Thursday morning, hundreds of thousands opened their pilgrimage in Mecca by circling Islam's holiest site, the Kaaba, the black cubic stone that Muslims face when they perform their daily prayers.

"For us it is a vacation away from work and daily life to renew yourself spiritually," said Ahmed Karkoutly, an American physician from Brownsville, Texas. "You feel you are part of a universe fulfilling God's will. It's a cosmic motion, orbiting the Kaaba."

Pilgrims filled the streets surrounding the Kaaba, some prostrating in prayer, others browsing outdoor markets to buy perfumes, fabrics, prayer beads and other souvenirs. In gleaming malls overlooking the Kaaba, pilgrims visited stores like the Body Shop or lined up at the Cinnabon.

The crowds then streamed into the tent cities set up outside town, wearing seamless white robes symbolizing the equality of mankind under God and chanting, "Labbeik, allahum, labbeik" -- Arabic for "I am here, Lord."

The heartier ones walked, carrying food, water and luggage. Others packed into buses and minibuses, some riding on the roof alongside baggage, as vehicles jammed highways in the hajj's annual epic of traffic control.

Most pilgrims went to Mina, a region in a desert valley 8 miles from Mecca. Ibrahim and tens of thousands of others went directly to Mount Arafat, where all pilgrims will gather Friday for the first major ritual of the pilgrimage.

Much of the day was spent settling into tents, with people from each Muslim country getting their own section of the sprawling temporary city.

"I've been hoping my whole life to be able to make this journey. Four times I didn't make the lottery, but this time God smiled on me," Ibrahim said, sitting on a foam mattress among suitcases.

In his tent, three fellow Egyptians debated the proper way to perform the complicated rituals. "Ask Sheik Hassan, he'll know," one of them said, and another quickly called the cleric traveling with their group on his mobile phone.

Some pilgrims climbed a hill on the edge of the tent city to pray at the top. Indonesian women helped each other clamber up the rocks. A Syrian woman wept as she held up her hands, praying for an ill relative. A crowd of Libyans chanted: "We have sinned, Lord. You are our heart, keep us from sin."

Saudi authorities estimate nearly 3 million pilgrims are attending this year's hajj. More than 1.6 million come from abroad. The rest are Saudis or foreigners who live in the kingdom.

More than 30,000 police and other security officers fanned out around the holy sites to help smooth pedestrian traffic in hopes of avoiding the deadly stampedes that have marred previous pilgrimages.

A stampede last year killed more than 360 people at Mina during a ritual symbolizing the stoning of the devil. The rush began when some pilgrims stumbled over luggage.

Saudi Arabia spent more than $1 billion over the past year to renovate the stoning site, where the crowds hurl stones at three stone walls symbolizing the devil.

After last year's stampede, the huge platform on which pilgrims stood to throw rocks was torn down and replaced by one with more exit and entrance ramps. In the coming years, the complex will be expanded to offer multiple levels for the stoning.

On Friday, pilgrims will spend the day and night in prayer and meditation at Mount Arafat, the site where Muhammad gave his final sermon in 632. They then return to Mina for the stoning ritual.