Many is an overstatement. You only really have SRAM and Campagnolo that are making decent groupsets and of the two, SRAM is the only one that makes MTB groupsets. MicroShift is there at the lower end and is probably best avoided unless it solves a specific problem you have. SunTour isn't doing groupsets anymore. You don't want to bother with the Chinese knockoffs of Shimano.
oic. SRAM was not as common here in Europe when I first started bicycletouring though. But I can see they are present on some Swedish webshops now though.