During the Sultan's rule, dancing was seen as lewd and disgusting behaviour, and was banned from 1370 onwards along with public smooching, holding hands and winking. Indeed, a poor unfortunate soul with a persistent squint was executed by the Sultan after unwittingly winking at a Royal Camel.
However, in spite of this authoritarian crackdown on nice stuff, the people still wanted to dance. In fear of their lives they danced only in the privacy of their own homes. The habit was for the members of the family to keep watch whilst one of them danced alone in a small cupboard or pantry.
After a short dance, the next family member would enter the cupboard for their turn to dance.
Following a number of terrible family disputes over whose turn it was to dance (and who had eaten the last cupcake in the pantry while they were dancing), a system of turn-taking was developed. This was called the line, and gave rise to the turn next in line. The most senior member of the family would be responsible for keeping the line in order, and after each dance would call the next person in line so they could take their turn.
Line Dancing had another brief moment of popularity in the 1970's, but was forever lost again after the Nuclear War on the Dancefloor.
Those who have mastered Line Dancing and have conquered it's complexities, are usually promoted to the Hokey Pokey circuit.