"I suppose it depends on who you ask. If we're talking only the major sects then there are only a handful but there are many smaller ones as well. Some could even include as few as three people. And, of course, those who are part of the righteous sects wouldn't consider demonic sects as legitimate." He doesn't particularly care about the distinction. Business is business.

Though all this is to say, there can be very many or very few. It depends on how you count them and whether or not someone cares to know them. Also canon never says.

"Though I doubt they could be counted in the hundreds. If that were so, then that'd be enough for an army." And then the Emperor would have to take notice.