There are differing views on the history of the holy rosary. The real origin is hidden behind the veil of a very long history.  Perhaps, at the very beginning, some spiritual people began with a collection of similar sized little pebbles, and soon found that stringing them together was a practical idea.

Perhaps the length of hide, with knots tied in it at intervals, came first.  We simply do not know.  But from time immemorial, holy and meditative people of many religions, and none, have found these items useful for their devotions.

The majority, nowadays, are probably used by Roman Catholics, but that is not to preclude those of the Islamic, Jewish, Buddhist, Hindu, Orthodox and Anglican Faiths, to name a few, having their rosary traditions.

We are talking here of an era when there was precious little in the way of written or even printed words for the mass of the faithful. The expense of even a Bible, once they were available and being printed, was way beyond the reach of most.

So they tended to stick to prayers that had been memorised, and, as long as they had the prayers in mind together with a reliable counting device, the praying of the Rosary became a habitual and deep part of devotional meditation.