There are large areas of British Columbia not at all suitable for farming due to lack of water, or mountains, but you still see cattle ranchers. On top of that, most of Alberta is classified as semi-arid because the Rockies block the vast majority of the rain. Alberta is easily the largest supplier of beef in the country. Crown land in both provinces gets opened up from spring until fall to allow for cattle grazing. It's fairly widespread in some parts of the world.