I tried various things, and the results were these: *I also deleted map.rwm every time in case that it had any effect

When the chance for Brigands was set to zero, the were 12 armies that appeared in the first four turns

When the probability was 100, 16 armies appeared in the first four turns

When I changed the category for brigands to peasant_revolt instead of brigands there still 16 armies in four turns

When I commented out the entire entry for Brignads (using ; at the beginnning of each line) there were four armies in four turns. I also commented out the entries for Brigands and slave_uprising in rebel_faction_descr_enums.txt and rebel_faction_descr.txt

Has anyone else experimented with rebels?