From recent forum events, I've seen that a large portion of accounts here are owned by people like the ones you are talking about, and often deal in shady ways (abusing multiple accounts, shitposting, scamming, selling account). I've seen a lot of them abuse bounty campaigns and signature campaigns run by not as careful managers.
I'm assuming you started doing google promotions, and also offered an affiliate-based type promotion? That's probably why so many people signed up, they are probably planning to make alternative accounts and farm the affiliate promotions.
You could try filter traffic from that area, or just block that region fully, I've always been under the impression that the region has never had a very important market that you could capitalize off anyway.
Thanks for Your answer.