From early October, close to two million believers will congregate to follow the 1,400-year-old tradition of Islam's Prophet Mohammed.
"This is like a beautiful dream. I will never forget these moments," Iraqi pilgrim Kazim Ibrahim, 69, said after reaching the holy city of Mecca.
While Ibrahim and other pilgrims are united by a common religious bond, this year's hajj comes with Muslim nations drawn together by widespread revulsion toward the Islamic State group jihadists.
Saudi Foreign Minister Prince Saud al-Faisal has branded IS "evil" and said the jihadists have distorted the image of Islam and Muslims.
Oil-rich Saudi Arabia is home to Islam's holiest sites, where it is waging a different kind of battle to protect pilgrims from two deadly viruses, Ebola and Middle East Respiratory Syndrome corona virus (MERS-CoV).
The deadliest Ebola epidemic on record has infected more than 6,200 people in west Africa and killed nearly half of them, according to the World Health Organisation (WHO).
This brought to 317 the number of MERS deaths in Saudi Arabia since it first appeared in September 2012.
Research by Saudi scientists indicates that camels play a role in the transmission of the virus to humans.
In June the WHO said a surge in MERS cases had receded but countries should remain vigilant ahead of pilgrimages to Saudi Arabia.
With such a large group of people concentrated in a limited area for a short time, "the hajj season constitutes a factor increasing the likelihood of outbreaks or epidemics of infectious diseases," acting Health Minister Adel Fakieh said in a statement.
