There are many origins of Lohri: all forming part of folklore. However, the main theme of Lohri is the belief that Lohri is the cultural celebration of the winter solstice(Phenomenon of Shortest day and longest night). Lohri is meant to be celebrated on the shortest day of the year.
According to folk lore, in ancient times Lohri was celebrated on winter solstice day. It is for this reason that people believe the Lohri night is meant to be the longest night of the year and on the day after Lohri, day light is meant to increase. Accordingly, the day after Lohri is celebrated as Maghi Sangrand when the days are meant to start getting longer. People believe nights gradually shorten “by the grain of one sesame seed” once the winter solstice passes.Wanna Know More?