MOUNT ARAFAT, Saudi Arabia, (AP) — Wearing white robes to symbolize purity and equality under God, millions of Muslims began Saturday their annual hajj pilgrimage by climbing a rocky desert hill outside Mecca.

Vast crowds of pilgrims started at dawn to ascend the Mountain of Mercy at Arafat, 12 miles (19 kilometers) outside Mecca, where Islam’s Prophet Muhammad is said to have delivered his farewell sermon.

The ascent of Arafat is the first event associated with the five-day hajj. Saudi authorities say that an estimated 2.5 million pilgrims are expected to participate.

“I’m very happy today. I can’t express my feelings,” said Badr Olgach, a 41-year old construction contractor from Turkey. “I wish and pray for the best, for all the Prophet Muhammad’s followers in the world,” said the father of two.

Since late Friday, pilgrims assembled around the mountain have been praying and reading Islam’s holy book, the Quran. While many were sleeping in tent compounds, others were setting up their small tents on sidewalks and streets.

This year’s hajj takes place amid an unprecedented wave of anti-government protests in the Arab world that has toppled autocrats in Tunisia, Egypt and Libya. Uprisings have also shaken regimes in Yemen, Bahrain and Syria.

While Muslims see the hajj as a time to seek forgiveness for one’s sins and for individual meditation on the faith, the unrest across the region remained at the forefront of the minds of many pilgrims.

“I wish for security to be maintained in my country. I pray to God that we in Syria be unified and stand shoulder to shoulder,” said sheik Ahmed Garman, 37, who led a group of Syrian pilgrims from Aleppo.

Syria since mid-March has witnessed a bloody crackdown on protesters in which the U.N. estimates some 3,000 people have been killed.

After sunset, the pilgrims will leave Arafat and headed to nearby Muzdalifah, where they collect pebbles for the next phase of the pilgrimage — the symbolic stoning of the devil represented by three pillars in Mina, just to the west.

The pilgrims then slaughter a camel, sheep or cow to celebrate the beginning of the Eid al-Adha, or the “Feast of the Sacrifice.”

Muslims from around the world wait a lifetime for a chance to make the pious journey in the footsteps of the Prophet Mohammed and Abraham, whom Muslims view as a forefather of Islam.