Cupping has been used for a very long time as a traditional therapy both in Asia and in Eastern Europe. It involves placing cups in strategic places, most often on the back, in which a vacuum is created to provide a degree of suction. You can think of it as a "massage in reverse", as the stimulation happens through the vacuum suction rather than through pressure.
This technique, like most others, can be individually adjusted to the strength required. It is ideal for children, as it can be very gentle and pleasant! My kids actually ask for it a lot, not minding the slight temporary marks that cupping leaves.