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Festival of the Dead or Feast of Ancestors is held by many cultures throughout the world in honor or recognition of deceased members of the community, generally occurring after the harvest in August, September, October, or November. As an example, the Ancient Egyptian Wag Festival took place in early August.
For the Hindus the ritual done for the dead ancestors is called Pitri Paksha. It is based on the Hindu lunar calendar and the period lasts for 15 days, falling towards the end of September. In Nepal, the popular festival of Gai Jatra honors the deceased, and is observed in the month of Bhadra, the date of which corresponds to the first day of the month of Gunla in the lunar Nepal Era calendar.
The Roman Catholic church celebrates three days of Allhallowtide from 31 October to 1 November, marking All Saints' Eve All Saints' Day and the second of November as All Souls' Day. The Mexican holiday celebrated at Hallowtide is called Dia de Los Muertos or Day of the Dead - prior to the Spanish colonisation and the conversion of local people to Christianity, this festival was celebrated in the summer time.
In many cultures a single event, Festival of the Dead, lasting up to 3 days, was held at the end of October and beginning of November; examples include the Peruvians, the Pacific Islanders, the people of the Tonga Islands, the ancient Persians, ancient Romans, and the northern nations of Europe. 
In the 21st century, European traditions mark the celebrations of Halloween.
It has been thought that the three day festival of the dead is a ritualistic remembrance of the deluge in which the first night, Halloween depicts the wickedness of the world before flood. The second night then celebrates the saved who survived the deluge and the last night celebrates those who would repopulate the Earth.