Recent research suggests that a lot of the early popular songs originated in Scotland. They were the result of poor Scots being thrown off their land by the Highland and Island clearances, so were about longing for home and of going to a promised land, common themes in gospel and early American folk music. But where do the terms come from? Here’s a snippet from ‘The Social Life of Scotland in the 18th century’ by H. Grey Graham:
“In the south country they had their gatherings in the evening, when, with music, singing and dancing, they also enacted the story of some old song, little dramas, not too refined, in which they showed what rustic skill and rude humour they could. On moonlight nights they held their favourite meetings in barn or cottage, called “Rockings” when young women brought their rocks and reels, or distaffs and spindles – where young men assembled, and to the accompaniment of the spinning of the wool and flax the song and merriment went round, till the company dispersed, and girls went home escorted by their swains, who carried gallantly their rocks over the corn-rigs and moor. When “rocks” were no more used, and spinning-wheels had taken their place, still by the familiar name of “rockings” were the merry social gatherings called. “
To add to the validity of this as an origin, there is of course the dances of jigs and reels, and there is a song that includes “reeling and a rocking” which the early rockers did till the break of dawn.