Helicopters hovered overhead and thousands of troops stood guard to organise roads flooded with men, women and children.
Chanting "Labaik Allahum Labaik" (I am responding to your call, God), many of them camped in small colourful tents and took shelter under trees to escape temperatures of around 40 degrees Celsius. Special sprinklers were set up to help cool the pilgrims.
In his annual sermon, top Saudi cleric Sheikh Abdulaziz al-Sheikh urged Muslims to avoid divisions, chaos and sectarianism, without explicitly speaking of the turmoil unleashed by the Arab Spring.
"You should know that you are targeted by your enemy... Who wants to spread chaos among you ... It's time to confront this."
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He did not speak specifically of Syria, where Sunni-led rebels backed by Saudi Arabia are at war with a regime led by Alawites -- an offshoot of Shiite Islam -- and closely allied with Shiite Iran and Hezbollah.
But the cleric recalled the Islamic prohibition of killing and aggression, while insisting there is "no salvation or happiness for the Muslim nation without adhering to the teachings of the religion."
Governor of Mecca province and head of the central hajj committee Prince Khaled al-Faisal said 1.38 million pilgrims had arrived from outside of the kingdom while only 117,000 hajj permits were issued for domestic pilgrims.
This puts the total number of pilgrims this year at almost 1.5 million, less than half of last year's 3.2 million, after Riyadh slashed hajj quotas.
Prince Khaled told the official SPA news agency late Sunday that authorities had turned back 70,000 nationals and expatriates for not carrying legal permits and had arrested 38,000 others for performing the hajj without a permit.