Most of the pilgrims have stayed in tents sectioned off by country and erected by the Saudi government over the site.
Pilgrims marched toward the hill, chanting "I am here, Lord," led by tour guides holding up umbrellas, branches or flags to keep their groups together in the pressing crowds.
A main theme of the Hajj is the equality of all mankind before God, symbolised by white robes worn by the pilgrims known as the "ihram".
However, tents organised by private tour groups often provide meals of lamb and rice, while those in government camps often give only meagre rations.
"Thank God, we're here, we're the guests of merciful God"
"We have 30 people in our tent. It was so crowded some people just slept outside," said Mohammed Awadallah, an Iraqi pilgrim.
"Still, thank God, we're here, we're the guests of merciful God."
A number of countries have held government lotteries in order to decide which citizens would be allowed to take part in the Hajj.
In most countries, the number of applicants far exceeds the quota Saudi Arabia sets for each country, which is 1,000 pilgrims per million of population.