is it a religious pilgrimage?
Yes, it  is an annual Islamic pilgrimage,  a mandatory religious duty for Muslims that must be carried out at least once in their lifetime
Hajj
 is an annual Islamic pilgrimage to Mecca, Saudi Arabia, the holiest city for Muslims. Hajj is a mandatory religious duty for Muslims that must be carried out at least once in their lifetime
when did two million pilgrims make the hajj UNANSWERABLE
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Hajj [SEP] Introduction
The Hajj (; ' "pilgrimage"; sometimes also spelled Hadj, Hadji or Haj in English) is an annual Islamic pilgrimage to Mecca, Saudi Arabia, the holiest city for Muslims. Hajj is a mandatory religious duty for Muslims that must be carried out at least once in their lifetime by all adult Muslims who are physically and financially capable of undertaking the journey, and can support their family during their absence. In Islamic terminology, Hajj is a pilgrimage made to the Kaaba, the "House of God", in the sacred city of Mecca in Saudi Arabia. It is one of the Five Pillars of Islam, alongside Shahadah, Salat, Zakat and Sawm.