Bihu is the oldest and most important festival of Assam. There are three Bihu festivals in Assam - in the months of Bohaag (Baisakh, the middle of April), Maagh (the middle of January), and Kaati (Kartik, the middle of October). Each Bihu coincides with a distinctive phase in the farming calendar. The most colourful of the three Bihu festival is the Spring festival "Bohag Bihu" or Rangali Bihu celebrated in the middle of April, which marks the beginning of the agricultural season.
Bihu is also the name given to the most widespread folk dance of Assam enjoyed by all, young and old, rich and poor. The dance is part of the Bihu festival that comes in mid-April, when harvesting is done, and continues for about a month. It also marks the beginning of the Asamese calendar.
Bihu dance is performed by young boys and girls in the open, though they do not mix with each other. The whole village participates in the dance as the dancers go from house to house. This form of dance is characterized by brisk stepping, flinging and flipping of hands and swaying of hips representing youthful passion. The performers sometimes sing songs, usually of love. The dance begins in a slow tempo, which gradually quickens as the dance proceeds. The enthralling beats of 'dhol', 'drum' and 'pepa' (Buffalo hornpipe) accompany the dance. It is mandatory to wear traditional attire like dhoti, gamocha and chadar and mekhala while performing Bihu.
Bihu dance, in its varied form, is also performed during various stages of cultivation and at the advent of new season. The most common formation is the circle or parallel rows. The Bihu demonstrates, through song and dance, the soul of the Assamese at its richest.